A copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether and preparation method thereof

Abstract

The present invention provides a copolymer of vinylidene fluoride and perfluoromethoxy vinyl ether and a preparation method thereof, comprising the following steps: adding a solvent, liquid paraffin oil and an initiator to a first reactor, cooling to ‑10~‑20 ℃; passing an inert gas to replace air in the first reactor, passing vinylidene fluoride to replace the inert gas, and heating to 50~60 ℃; passing an inert gas to replace air in the second reactor, passing perfluoromethoxy vinyl ether and vinylidene fluoride to obtain a mixed gas; passing the mixed gas into the first reactor, and a polymerization reaction occurs at a temperature of 50~70 ℃ and a pressure of 10~1000pis; after the reaction is completed, cooling to room temperature, filtering, washing, and drying to obtain the copolymer. The present invention uses solvent polymerization, does not need to use emulsifiers such as perfluorocarbon miscellaneous oxygen carboxylic acid ammonium or perfluorocarbon carboxylic acid salts, and does not produce waste water, the solvent is reusable, is environmentally friendly, and is suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of polymers, and in particular to a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether and a preparation method thereof. Background Art

[0002] The main component of fluororubber is fluorinated polymer, which can be polymerized from vinyl fluoride and other monomers. It is a synthetic polymer material, such as ethylene-vinyl fluoride copolymer (FKM), tetrafluoroethylene-isocyanate copolymer (FFKM) and ethylene-fluorine-propylene terpolymer (FEPM). These fluorinated polymer components give fluororubber excellent heat resistance, oil resistance and chemical corrosion resistance, making it suitable for various extreme environments, such as aviation, aerospace, automobile and chemical industries.

[0003] At present, the polymerization process of fluorinated polymers requires the use of emulsifiers such as ammonium perfluorocarbon carboxylates or perfluorocarbon carboxylates, and perfluorocarbon carboxylates with six carbon atoms or more have been listed as PFAS (per- and polyfluoroalkyl substances) in Europe and the United States. PFAS substances are not easy to decompose, and some types have been proven to accumulate in the environment and in people's bodies. Exposure to certain types of PFAS may have serious health effects and are gradually being listed as banned substances.

[0004] Therefore, it is particularly important to develop a method for preparing fluorinated polymers without using emulsifiers such as ammonium perfluorocarbon oxycarboxylates or perfluorocarbon carboxylates. Summary of the invention

[0005] The object of the present invention is to provide a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether and a preparation method thereof. The preparation method uses solvent polymerization, does not require the use of emulsifiers such as perfluorocarbon oxycarboxylic acid ammonium or perfluorocarbon carboxylic acid salts, does not generate waste water, the solvent can be reused, is environmentally friendly, and is suitable for large-scale production.

[0006] The first aspect of the present invention provides a method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether, comprising the following steps:

[0007] S1. Add solvent, liquid paraffin oil and initiator into the first reaction kettle and cool to -10 to -20°C;

[0008] S2, introducing inert gas into the first reaction kettle to replace the air, then introducing vinylidene fluoride to replace the inert gas, and heating to 50-60° C.;

[0009] S3, introducing an inert gas into the second reaction kettle to replace the air, and then introducing perfluoromethoxyvinyl ether and vinylidene fluoride to obtain a mixed gas;

[0010] S4, passing the mixed gas in the second reaction kettle into the first reaction kettle, and causing polymerization reaction at a temperature of 50-60° C. and a pressure of 10-1000 pis;

[0011] S5. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0012] Preferably, in step S1, the initiator is any one of peroxides such as diisopropyl peroxydicarbonate (IPP) or tri-amyl peroxypivalate (TAPP).

[0013] Preferably, in step S1, the solvent is a fluorocarbon ether solvent, for example, any one of the commercially available 3M fluorocarbon ether solvents F5805, F5806 or F5808.

[0014] Preferably, in step S1, the usage ratio of the solvent, liquid paraffin oil and initiator is (600-800) ml:1 g:(0.1-1) g, more preferably 700 ml:1 g:(0.3-0.5) g.

[0015] Preferably, the specific operation of step S2 is: use a mechanical pump to extract the gas in the reaction kettle, introduce inert gas to a pressure of 40 to 60 pis, and repeat several times (preferably five times); use a mechanical pump to extract the gas in the reaction kettle, introduce vinylidene fluoride (VDF) to a pressure of 40 to 60 pis, and repeat several times (preferably five times); stir at a speed of 500 to 700 rpm and heat to 50 to 60°C.

[0016] Preferably, in step S3, the mass ratio of perfluoromethoxyvinyl ether to vinylidene fluoride is (2-8):(5-11), for example: 1:3, 6:7, etc.

[0017] Preferably, in step S4, the temperature is 55-60° C., and the pressure is 10-200 pis.

[0018] Preferably, in step S5, the pressure is reduced to 5-10 pis, cooled to room temperature, filtered, washed, and dried at 50-60° C. for 18-30 hours to obtain a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0019] Preferably, the inert gas is nitrogen.

[0020] The second aspect of the present invention provides a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether, which is prepared by the above-mentioned preparation method.

[0021] The third aspect of the present invention provides an application of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether in the preparation of a lithium ion battery electrode material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) Compared with the conventional method of using emulsifiers such as ammonium perfluorocarbon carboxylates or perfluorocarbon carboxylates for copolymerization, the present invention uses solvent copolymerization, does not require the use of emulsifiers, and is environmentally friendly.

[0024] (2) The traditional method generates more than ten tons of wastewater per ton of product. The wastewater contains calcium chloride, especially perfluorocarbon carboxylates, which seriously affect the environment. The preparation process of the present invention does not use deionized water and does not generate wastewater, which greatly reduces the subsequent wastewater treatment costs.

[0025] (3) The solvent used in the present invention can be recycled and reused, which greatly reduces the production cost.

[0026] (4) The preparation process of the present invention does not require emulsification or demulsification, the process is simple, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether prepared in Example 1 of the present invention.

[0029] Figure 2 The copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether, comprising the following steps:

[0035] In a clean 1L autoclave, 700ml of 3M F5805 solvent, 1g of liquid paraffin oil, and 0.5g of IPP were added, the autoclave was covered, and the autoclave was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the autoclave was extracted with a mechanical pump, and high-purity nitrogen was introduced to a pressure of 50pis, and repeated five times). The nitrogen was replaced with VDF five times in the same operation, the stirring speed was 600 rpm, and the autoclave was heated to 60°C; another 5L clean autoclave was replaced with nitrogen, 30g of perfluoromethoxyvinyl ether and 90g of vinylidene fluoride were added under vacuum, and the mixed gas was introduced into the 1L autoclave under stirring, the pressure was 150pis, and the temperature was 60°C to start polymerization. The temperature was maintained at 60°C, and the pressure gradually decreased. After 10 hours, the pressure dropped to 5pis, and the insulation was stopped. The autoclave was cooled to room temperature, the lid was opened after venting, and suction was filtered. 200ml The mixture was washed with 3M F5805 and dried at 60°C for 24 hours to obtain 115 g of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0036] The vinylidene fluoride and perfluoromethoxy vinyl ether copolymer prepared in this example is shown in Figure 1 .

[0037] Example 2

[0038] In a clean 1L autoclave, 700ml of 3M F5806 solvent, 1g of liquid paraffin oil, and 0.3g of IPP were added, the autoclave was covered, and the autoclave was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the autoclave was extracted with a mechanical pump, and high-purity nitrogen was introduced to a pressure of 50pis, and repeated five times). The nitrogen was replaced with VDF five times in the same operation, the stirring speed was 600 rpm, and the autoclave was heated to 55°C; another 5L clean autoclave was replaced with nitrogen, 60g of perfluoromethoxyvinyl ether and 70g of vinylidene fluoride were added under vacuum, and the mixed gas was introduced into the 1L autoclave under stirring, the pressure was 150pis, and the temperature was 55°C to start polymerization. The temperature was maintained at 55°C, and the pressure gradually decreased. After 8 hours, the pressure dropped to 5pis, and the insulation was stopped. The autoclave was cooled to room temperature, the lid was opened after venting, and the autoclave was filtered with suction, and 200ml The mixture was washed with 3M F5806 and dried at 60°C for 24 hours to obtain 110 g of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0039] The vinylidene fluoride and perfluoromethoxy vinyl ether copolymer prepared in this example is shown in Figure 2 .

[0040] Example 3

[0041] In a clean 1L autoclave, 700ml of 3M F5805 solvent, 1g of liquid paraffin oil, and 0.5g of TAPP were added, the autoclave was covered, and the autoclave was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the autoclave was extracted with a mechanical pump, and high-purity nitrogen was introduced to a pressure of 50pis, and repeated five times). The nitrogen was replaced with VDF five times in the same operation, the stirring speed was 600 rpm, and the autoclave was heated to 55°C. Another 5L clean autoclave was replaced with nitrogen, 30g of perfluoromethoxyvinyl ether and 90g of vinylidene fluoride were added under vacuum, and the mixed gas was introduced into the 1L autoclave under stirring. The pressure was 150pis and the temperature was 55°C to start polymerization. The temperature was maintained at 55°C, and the pressure gradually decreased. After 10 hours, the pressure dropped to 5pis, and the insulation was stopped. The autoclave was cooled to room temperature, the lid was opened after venting, and the autoclave was filtered with suction. 200ml The mixture was washed with 3M F5805 and dried at 80°C for 24 hours to obtain 113 g of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0042] Example 4

[0043] In a clean 1L autoclave, 700ml of 3M 5806 solvent, 1g of liquid paraffin oil, and 0.5g of TAPP were added, the autoclave was covered, and the autoclave was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the autoclave was extracted with a mechanical pump, and high-purity nitrogen was introduced to a pressure of 50pis, and repeated five times). The nitrogen was replaced with VDF five times in the same operation. The stirring speed was 600 rpm and the autoclave was heated to 60°C. Another 5L clean autoclave was replaced with nitrogen, and 30g of perfluoromethoxyvinyl ether and 90g of vinylidene fluoride were added under vacuum. The mixed gas was introduced into the 1L autoclave under stirring, and the polymerization was started at a pressure of 150pis and a temperature of 60°C. The temperature was maintained at 60°C, and the pressure was gradually reduced. After 10 hours, the pressure dropped to 5pis, and the insulation was stopped. The autoclave was cooled to room temperature, the lid was opened after venting, and the autoclave was filtered with suction. 200ml The mixture was washed with 3M 5806 and dried at 60°C for 24 hours to obtain 115 g of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0044] Example 5

[0045] In a clean 1L autoclave, 700ml of 3M F5808 solvent, 1g of liquid paraffin oil, and 0.5g of TAPP were added, the autoclave was covered, and the autoclave was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the autoclave was pumped out with a mechanical pump, and high-purity nitrogen was introduced to a pressure of 50pis, and repeated five times). The nitrogen was replaced with VDF five times in the same operation, the stirring speed was 600 rpm, and the autoclave was heated to 60°C. Another 5L clean autoclave was replaced with nitrogen, 30g of perfluoromethoxyvinyl ether and 90g of vinylidene fluoride were added under vacuum, and the mixed gas was introduced into the 1L autoclave under stirring. The pressure was 150pis and the temperature was 60°C to start polymerization. The temperature was maintained at 60°C, and the pressure gradually decreased. After 10 hours, the pressure dropped to 5pis, and the insulation was stopped. The autoclave was cooled to room temperature, the lid was opened after venting, and the autoclave was filtered with suction, and 200ml The mixture was washed with 3M F5808 and dried at 60°C for 24 hours to obtain 116 g of a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

[0046] Example 6

[0047] The vinylidene fluoride and perfluoromethoxyvinyl ether copolymers prepared in Examples 1-5 were used in the preparation of low-temperature resistant fluororubber.

[0048] Example 7

[0049] The vinylidene fluoride and perfluoromethoxyvinyl ether copolymer prepared in Examples 1-5 was used in the preparation of a low-temperature resistant sealing ring.

[0050] Example 8

[0051] The vinylidene fluoride and perfluoromethoxyvinyl ether copolymers prepared in Examples 1-5 are used in the preparation of lithium ion battery electrode materials.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether, characterized in that: The following steps are involved: S1. Add solvent, liquid paraffin oil and initiator into the first reaction kettle and cool to -10 to -20°C; the solvent is a fluorocarbon ether solvent; the amount ratio of the solvent, liquid paraffin oil and initiator is (600 to 800) ml: 1 g: (0.1 to 1) g; S2, introducing inert gas into the first reaction kettle to replace the air, then introducing vinylidene fluoride to replace the inert gas, and heating to 50-60° C.; S3, introducing an inert gas into the second reaction kettle to replace the air, and then introducing perfluoromethoxyvinyl ether and vinylidene fluoride to obtain a mixed gas; the mass ratio of perfluoromethoxyvinyl ether to vinylidene fluoride is (2-8):(5-11); S4, passing the mixed gas in the second reaction kettle into the first reaction kettle, and causing polymerization reaction at a temperature of 50-60° C. and a pressure of 10-1000 pis; S5. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

2. The method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether according to claim 1, characterized in that: In step S1, the initiator is any one of IPP or TAPP.

3. The method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether according to claim 1, characterized in that: In step S4, the temperature is 55-60° C., and the pressure is 10-200 pis.

4. The method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether according to claim 1, wherein in step S5, the pressure is reduced to 5-10 pis, cooled to room temperature, filtered, washed, and dried at 50-60°C for 18-30 hours to obtain a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether.

5. The method for preparing a copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether according to claim 1, characterized in that: The inert gas is nitrogen.

6. A copolymer of vinylidene fluoride and perfluoromethoxyvinyl ether, characterized in that: The method is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the vinylidene fluoride and perfluoromethoxyvinyl ether copolymer according to claim 6 in the preparation of low-temperature resistant fluororubber, sealing ring and lithium ion battery electrode material.

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