Preparation process of perfluoroether elastomer
By introducing 3-hydroxy-2-trifluoromethylpropionic acid as a third monomer, the preparation process of perfluoroether elastomers was optimized, solving the problems of low polymerization efficiency and molecular weight control. This resulted in the preparation of perfluoroether elastomers with high yield and high molecular weight, improving material properties and reducing costs.
Patent Information
- Application Number
- CN202511791762.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-01
- Publication Date
- 2026-02-10
AI Technical Summary
Traditional VDF/PMVE binary copolymer preparation processes suffer from low polymerization efficiency, limited molecular weight control, difficulty in obtaining high molecular weight perfluoroether elastomers, and improper selection of the third monomer may inhibit the polymerization reaction or introduce side reactions.
3-hydroxy-2-trifluoromethylpropionic acid (MAF-OH) was used as the third monomer. It was prepared by acidic catalytic hydrolysis and emulsion copolymerization was carried out in a liquid nitrogen bath. The polymerization process was optimized by combining low-temperature demulsification and vacuum drying.
It significantly increased the polymerization yield by 80%-120%, obtained high molecular weight perfluoroether elastomers, improved the mechanical properties and durability of the material, and reduced production costs.
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Figure CN121495034A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a process for preparing perfluoroether elastomers, particularly a process for preparing high-performance perfluoroether elastomers by ternary copolymerization of 1,1-difluoroethylene (VDF), perfluoromethyl vinyl ether (PMVE) and a third monomer 3-hydroxy-2-trifluoromethylpropionic acid (MAF-OH). Background Technology
[0002] Perfluoroether elastomers are a class of special polymer materials with excellent high temperature resistance, chemical corrosion resistance, weather resistance and high elasticity. They play an irreplaceable role in high-end industrial fields such as aerospace, semiconductor, chemical and automotive. Among them, fluororubber made by copolymerization of VDF and PMVE is an important variety. Its flexibility and low temperature performance benefit from the introduction of PMVE. However, the traditional preparation process of VDF / PMVE binary copolymers has some limitations. First, its polymerization efficiency (yield) is usually not high, which leads to increased production costs and low raw material utilization. Second, the ability to control the molecular weight during polymerization is limited, making it difficult to stably obtain high molecular weight products. High molecular weight is crucial to ensuring the mechanical properties of elastomers and the durability of the final product. In order to improve polymerization efficiency or introduce specific functional groups, those skilled in the art usually try to introduce a third monomer. However, the selection of the third monomer is crucial. If its reactivity does not match that of the main monomer, or if it is unstable under high-intensity polymerization conditions, it may not only fail to promote polymerization but may also inhibit the polymerization reaction, leading to a further decrease in yield and molecular weight, or the introduction of undesirable side reactions. Therefore, there is an urgent need for a preparation process for perfluoroether elastomers to solve the technical problems mentioned above. Summary of the Invention
[0003] To overcome the aforementioned deficiencies of the prior art, the present invention provides a preparation process for perfluoroether elastomers to solve the problems existing in the background art.
[0004] To achieve the above objectives, the present invention provides the following technical solution: a process for preparing a perfluoroether elastomer, the process comprising the following steps: A process for preparing a perfluoroether elastomer, the process comprising the following steps: S1, Preparation of the third monomer: 2-trifluoromethylacrylic acid was added to deionized water and hydrolyzed at 80°C for 24 hours in the presence of an acidic catalyst. Then, it was freeze-dried at -20°C and atmospheric pressure for 10 hours to obtain 3-hydroxy-2-trifluoromethylpropionic acid. S2, Emulsion Copolymerization: Potassium persulfate initiator and the 3-hydroxy-2-trifluoromethylpropionic acid obtained in S1 are dissolved in 60 mL of deionized water to form an aqueous solution. After purging with nitrogen to remove oxygen, the solution is transferred to a reaction vessel. The reaction system is then placed in a liquid nitrogen bath and cooled to below -10°C. A stoichiometric ratio of 1,1-difluoroethylene and perfluoromethyl vinyl ether monomers is introduced. The reaction vessel is sealed and first naturally heated to room temperature, then heated to 80°C within 1 hour. The emulsion copolymerization reaction is carried out at a stirring speed of 300 rpm and then kept at 80°C for 5 hours to obtain the copolymer product. S3. Post-processing: The copolymer obtained in S2 is placed in a low-temperature water bath at 0-5℃ for 24 hours to demulsify, and then filtered, resuspended and washed with 10-20 times the volume of deionized water, and dried to obtain the perfluoroether elastomer.
[0005] Preferably, the acidic catalyst is concentrated sulfuric acid; Step S2, after being kept at a constant temperature of 80°C for 5 hours, also includes the step of naturally cooling the reactor to room temperature.
[0006] Preferably, the amount of potassium persulfate initiator used in step S2 is 0.1%-0.5% of the total molar amount of 1,1-difluoroethylene and perfluoromethyl vinyl ether.
[0007] Preferably, in step S1, the mass ratio of 2-trifluoromethylacrylic acid to deionized water is 1:(90-110).
[0008] Preferably, in step S2, the reactor is equipped with a heating program: the reaction system is first heated to room temperature, and then heated to 80°C within 1 hour.
[0009] Preferably, step S3 includes the following sub-steps: a) Demulsification: Place the copolymer in a low temperature environment of 0-10℃ and let it stand for 20-28 hours to allow the copolymer to fully coagulate and settle; b) Filtration: The copolymerized product after coagulation and sedimentation is filtered to obtain a solid product; c) Washing: The solid product obtained after filtration is resuspended in 10-20 times its mass or volume of water and then subjected to auxiliary filtration to finally obtain the washed solid product. b) Drying: The washed solid product is dried by vacuum drying at a temperature of 50-60°C for 12-24 hours to obtain the purified perfluoroether elastomer.
[0010] Preferably, the drying in step b is performed in a vacuum drying oven at 50-60°C for 12-24 hours.
[0011] Preferably, in step b, the filtration process is achieved by Buchner funnel filtration, sand core funnel filtration, or centrifugal separation.
[0012] Preferably, in step a, the low-temperature environment is achieved by an ice-water bath or a low-temperature constant-temperature bath.
[0013] Preferably, in step c, the resuspending and auxiliary filtering steps are repeated once or more.
[0014] The technical effects and advantages of this invention are as follows: This invention significantly improves polymerization efficiency by introducing a specific third monomer, MAF-OH. Compared with the traditional method without adding MAF-OH, the yield is increased by about 80% to 120%, effectively improving raw material utilization and production efficiency, and reducing production costs.
[0015] The process described in this invention achieves high yield while stably obtaining high molecular weight polymer products. The number-average molecular weight (Mn) of the resulting elastomer is significantly higher than that of traditional binary copolymers, thereby endowing the material with superior mechanical properties and durability.
[0016] This invention successfully introduces polar groups into the molecular chain of fluoroelastomers by introducing a self-made hydroxyl-containing third monomer, MAF-OH, which effectively improves the polarity and compatibility of the polymer. The resulting perfluoroether elastomer is a white powder with excellent elasticity, high temperature resistance, and chemical resistance, and has broad application prospects in the preparation of high-end sealing materials, gaskets, and hoses. Attached Figure Description
[0017] Figure 1 This is a flowchart illustrating the preparation process of the perfluoroether elastomer shown in this invention. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the morphologies of the various structures described in the following embodiments are merely illustrative. The preparation process of a perfluoroether elastomer involved in the present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] Example 1
[0020] Reference Figure 1 This invention provides a process for preparing a perfluoroether elastomer, which is obtained by terpolymerization of 1,1-difluoroethylene (VDF), perfluoromethyl vinyl ether (PMVE) and 3-hydroxy-2-trifluoromethylpropionic acid (MAF-OH).
[0021] Reference Figure 1 This invention provides a preparation process for perfluoroether elastomers, the preparation process including the following steps: S1, Preparation of the third monomer: 2-trifluoromethylacrylic acid was added to deionized water and hydrolyzed at 80°C for 24 hours in the presence of an acidic catalyst. Then, it was freeze-dried at -20°C and atmospheric pressure for 10 hours to obtain 3-hydroxy-2-trifluoromethylpropionic acid. S2, Emulsion Copolymerization: Potassium persulfate initiator and the 3-hydroxy-2-trifluoromethylpropionic acid obtained in S1 are dissolved in 60 mL of deionized water to form an aqueous solution. After purging with nitrogen to remove oxygen, the solution is transferred to a reaction vessel. The reaction system is then placed in a liquid nitrogen bath and cooled to below -10°C. A stoichiometric ratio of 1,1-difluoroethylene and perfluoromethyl vinyl ether monomers is introduced. The reaction vessel is sealed and first naturally heated to room temperature, then heated to 80°C within 1 hour. The emulsion copolymerization reaction is carried out at a stirring speed of 300 rpm and then kept at 80°C for 5 hours to obtain the copolymer product. S3. Post-processing: The copolymer obtained in S2 is placed in a low-temperature water bath at 0-5℃ for 24 hours to demulsify, and then filtered, resuspended and washed with 10-20 times the volume of deionized water, and dried to obtain the perfluoroether elastomer.
[0022] In the embodiments of this application, the preferred acidic catalyst is concentrated sulfuric acid.
[0023] The perfluoroether elastomer prepared in this application is a white powder.
[0024] The advantages of using acid catalysts are: catalytic ester / anhydride hydrolysis: although MAF is an acid, its hydrolysis process may involve intramolecular cyclization or a transition state with water addition, and the protonated acidic environment can effectively catalyze this process; Suppressing side reactions: The carbon-carbon double bond (C=C) in the MAF molecule is very reactive under alkaline conditions, readily undergoing Michael addition or polymerization reactions, leading to the formation of dimers, oligomers, or cross-linked byproducts instead of the target product MAF-OH. An acidic environment can protonate the double bond, significantly suppressing these side reactions and ensuring that the hydrolysis reaction proceeds in the intended direction.
[0025] Example 2
[0026] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: Prepare MAF-OH according to the method in Example 1 for later use.
[0027] Step 2: Accurately weigh 2.0 mmol KPS and 4.2 mmol MAF-OH, place them in a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (80 mmol) and PMVE liquid (24 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain perfluoroether elastomer.
[0028] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 68%, and its number-average molecular weight (Mn) was determined to be 33476 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 80 mol.% MAF-OH concentration: 70mM; Total monomer feed amount: 200 mmol; Actual VDF dosage: 160 mmol; Actual PMVE dosage: 40 mmol; KPS dosage: Add 1% of the total molar amount of VDF and PMVE.
[0029] Where mmol is millimole; mol.% represents the mole percentage; mM stands for millimoles per liter; "Number-average molecular weight (Mn)" is a key parameter used in this field to characterize the size of polymer molecules. It is defined as the total mass of all polymer molecules in the polymer sample being tested, divided by the total number of moles of all polymer molecules in the sample.
[0030] Example 3
[0031] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: Prepare MAF-OH according to the method in Example 1 for later use.
[0032] Step 2: Accurately weigh 1.2 mmol KPS and 4.2 mmol MAF-OH, place them in a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (96 mmol) and PMVE liquid (19.8 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain perfluoroether elastomer.
[0033] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 65%, and its number-average molecular weight (Mn) was determined to be 34678 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 80 mol.% MAF-OH concentration: 70 mM (equivalent to 4.2 mmol in 60 mL of aqueous phase); Total monomer feed amount: 120 mmol; Actual VDF dosage: 96 mmol; Actual PMVE dosage: 19.8 mmol; KPS dosage: Add approximately 1.04% of the total molar amount of VDF and PMVE (115.8 mmol).
[0034] Example 4
[0035] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: In this comparative example, no third monomer MAF-OH is added; the copolymerization reaction is carried out directly.
[0036] Step 2: Accurately weigh 2.0 mmol KPS into a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (160 mmol) and PMVE liquid (40 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain the fixed product.
[0037] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 38%, and its number-average molecular weight (Mn) was determined to be 28956 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 80 mol.% MAF-OH concentration: 0 mM; Total monomer feed amount: 200 mmol; Actual VDF dosage: 160 mmol; Actual PMVE dosage: 40 mmol; KPS dosage: Add 1% of the total molar amount of VDF and PMVE.
[0038] Example 5
[0039] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: In this comparative example, no third monomer MAF-OH is added; the copolymerization reaction is carried out directly.
[0040] Step 2: Accurately weigh 1.2 mmol KPS into a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (96 mmol) and PMVE liquid (24 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain the fixed product.
[0041] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 36%, and its number-average molecular weight (Mn) was determined to be 27865 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 80 mol.% MAF-OH concentration: 0 mM; Total monomer feed amount: 120 mmol; Actual VDF dosage: 96 mmol; Actual PMVE dosage: 24 mmol; KPS dosage: Add 1% of the total molar amount of VDF and PMVE.
[0042] Example 6
[0043] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: Prepare MAF-OH according to the method in Example 1 for later use; Step 2: Accurately weigh 2.0 mmol KPS and 4.2 mmol MAF-OH, place them in a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (140 mmol) and PMVE liquid (55.8 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain perfluoroether elastomer.
[0044] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 70%, and its number-average molecular weight (Mn) was determined to be 35643 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 70 mol.% MAF-OH concentration: 70 mM (equivalent to 4.2 mmol in 60 mL of aqueous phase); Total monomer feed amount: 200 mmol; Actual VDF dosage: 140 mmol; Actual PMVE dosage: 55.8 mmol; KPS dosage: Add approximately 1.02% of the total molar amount of VDF and PMVE (195.8 mmol).
[0045] Example 7
[0046] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: Prepare MAF-OH according to the method in Example 1 for later use; Step 2: Accurately weigh 1.2 mmol KPS and 4.2 mmol MAF-OH, place them in a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (84 mmol) and PMVE liquid (31.8 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain perfluoroether elastomer.
[0047] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 73%, and its number-average molecular weight (Mn) was determined to be 32453 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 70 mol.% MAF-OH concentration: 70 mM (equivalent to 4.2 mmol in 60 mL of aqueous phase); Total monomer feed amount: 120 mmol; Actual VDF dosage: 84 mmol; Actual PMVE dosage: 31.8 mmol; KPS dosage: Add approximately 1.04% of the total molar amount of VDF and PMVE (115.8 mmol).
[0048] Example 8
[0049] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: In this comparative example, no third monomer MAF-OH is added; the copolymerization reaction is carried out directly.
[0050] Step 2: Accurately weigh 1.6 mmol KPS into a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (112 mmol) and PMVE liquid (48 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain the fixed product.
[0051] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 32%, and its number-average molecular weight (Mn) was determined to be 29876 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 70 mol.% MAF-OH concentration: 0 mM; Total monomer feed amount: 160 mmol; Actual VDF dosage: 112 mmol; Actual PMVE dosage: 48 mmol; KPS dosage: Add 1% of the total molar amount of VDF and PMVE.
[0052] Example 9
[0053] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: Prepare MAF-OH according to the method in Example 1 for later use; Step 2: Accurately weigh 1.6 mmol KPS and 2.13 mmol MAF-OH, place them in a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (96 mmol) and PMVE liquid (61.87 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain perfluoroether elastomer.
[0054] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 56%, and its number-average molecular weight (Mn) was determined to be 35675 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 60 mol.% MAF-OH concentration: 35.5 mM (equivalent to 2.13 mmol in 60 mL of aqueous phase); Total monomer feed amount: 160 mmol; Actual VDF dosage: 96 mmol; Actual PMVE dosage: 61.87 mmol; KPS dosage: Add approximately 1.01% of the total molar amount of VDF and PMVE (157.87 mmol).
[0055] Example 10
[0056] A process for preparing a perfluoroether elastomer involves emulsion polymerization using the following general steps: Step 1: In this comparative example, no third monomer MAF-OH is added; the copolymerization reaction is carried out directly.
[0057] Step 2: Accurately weigh 1.6 mmol KPS into a beaker, add 60 mL of deionized water, stir to dissolve and form a homogeneous aqueous solution, bubble with nitrogen to remove oxygen for 20 minutes, and then transfer the solution to a high-pressure reactor. The reactor was placed in a liquid nitrogen bath to freeze the material. VDF gas (96 mmol) and PMVE liquid (64 mmol) were introduced sequentially. The reactor was sealed and allowed to heat naturally to room temperature. Then, the temperature was increased to 80°C in an oil bath over 1 hour. Stirring (300 rpm) was started to carry out the emulsion copolymerization reaction. After the reaction was completed, the reactor was kept in a constant temperature water bath for 5 hours. Step 3: Cool the emulsion after reaction to room temperature, let it stand in a 5°C water bath for 24 hours to break the emulsion, filter and collect the solid polymer, resuspend it with 10 times the volume of deionized water and filter it, repeat the washing once, and finally dry the solid product under vacuum at 60°C for 12 hours to constant weight to obtain the fixed product.
[0058] Product characterization: The product obtained in this embodiment, after weighing and calculation, had a yield of 28%, and its number-average molecular weight (Mn) was determined to be 29876 by gel permeation chromatography (GPC). In this embodiment, the formula is described as follows: VDF feed ratio: 60 mol.%; MAF-OH concentration: 0 mM; total monomer feed amount: 160 mmol; actual VDF feed amount: 96 mmol; actual PMVE feed amount: 64 mmol; KPS dosage: 1% of the total molar amount of VDF and PMVE.
[0059] Summarize Examples 2-10 and generate corresponding data lists for each example, as follows:
[0060] Based on the data list of the above embodiments, the following conclusions can be clearly drawn: Conclusion 1: Under the same VDF feed ratio, the polymerization yield of the example with added MAF-OH increased by about 80%-120% compared with the comparative example without added MAF-OH, indicating that the addition of MAF-OH has a significant effect on improving the polymerization reaction efficiency. Conclusion 2: In all examples with added MAF-OH, the number average molecular weight (Mn) remained in the range of 32,000-35,000, which was higher than that of the comparative examples without added MAF-OH (the molecular weight was lower than 30,000). This indicates that the process can maintain a high molecular weight of the product while improving the yield.
[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A preparation process for a perfluoroether elastomer, characterized in that, The preparation process includes the following steps: S1, Preparation of the third monomer: 2-trifluoromethylacrylic acid was added to deionized water and hydrolyzed at 80°C for 24 hours in the presence of an acidic catalyst. Then, it was freeze-dried at -20°C and atmospheric pressure for 10 hours to obtain 3-hydroxy-2-trifluoromethylpropionic acid. S2, Emulsion Copolymerization: Potassium persulfate initiator and the 3-hydroxy-2-trifluoromethylpropionic acid obtained in S1 are dissolved in 60 mL of deionized water to form an aqueous solution. After purging with nitrogen to remove oxygen, the solution is transferred to a reaction vessel. The reaction system is then placed in a liquid nitrogen bath and cooled to below -10°C. A stoichiometric ratio of 1,1-difluoroethylene and perfluoromethyl vinyl ether monomers is introduced. The reaction vessel is sealed and first naturally heated to room temperature, then heated to 80°C within 1 hour. The emulsion copolymerization reaction is carried out at a stirring speed of 300 rpm and then kept at 80°C for 5 hours to obtain the copolymer product. S3. Post-processing: The copolymer obtained in S2 is placed in a low-temperature water bath at 0-5℃ for 24 hours to demulsify, and then filtered, resuspended and washed with 10-20 times the volume of deionized water, and dried to obtain the perfluoroether elastomer.
2. The preparation process of the perfluoroether elastomer according to claim 1, characterized in that: The acidic catalyst is concentrated sulfuric acid; Step S2, after being kept at a constant temperature of 80°C for 5 hours, also includes the step of naturally cooling the reactor to room temperature.
3. The preparation process of the perfluoroether elastomer according to claim 1, characterized in that: The amount of potassium persulfate initiator mentioned in step S2 is 0.1%-0.5% of the total molar amount of 1,1-difluoroethylene and perfluoromethyl vinyl ether.
4. The preparation process of the perfluoroether elastomer according to claim 1, characterized in that: In step S1, the mass ratio of 2-trifluoromethylacrylic acid to deionized water is 1:(90-110).
5. The preparation process of the perfluoroether elastomer according to claim 1, characterized in that: In step S2, the reactor is equipped with a heating program: the reaction system is first heated to room temperature, and then heated to 80°C within 1 hour.
6. The preparation process of the perfluoroether elastomer according to claim 1, characterized in that: Step S3 includes the following sub-steps: a) Demulsification: Place the copolymer in a low temperature environment of 0-10℃ and let it stand for 20-28 hours to allow the copolymer to fully coagulate and settle; b) Filtration: The copolymerized product after coagulation and sedimentation is filtered to obtain a solid product; c) Washing: The solid product obtained after filtration is resuspended in 10-20 times its mass or volume of water and then subjected to auxiliary filtration to finally obtain the washed solid product. b) Drying: The washed solid product is dried by vacuum drying at a temperature of 50-60°C for 12-24 hours to obtain the purified perfluoroether elastomer.
7. The preparation process of the perfluoroether elastomer according to claim 6, characterized in that: The drying process described in step b involves drying in a vacuum drying oven at 50-60°C for 12-24 hours.
8. The preparation process of the perfluoroether elastomer according to claim 6, characterized in that: In step b, the filtration process is achieved through Buchner funnel filtration, sand core funnel filtration, or centrifugal separation.
9. The preparation process of the perfluoroether elastomer according to claim 6, characterized in that: In step a, the low-temperature environment is achieved through an ice-water bath or a low-temperature constant temperature bath.
10. The preparation process of the perfluoroether elastomer according to claim 6, characterized in that: In step c, the resuspension and auxiliary filtration steps are repeated once or more.