High-purity polyvinylidene fluoride resin as well as preparation method and application thereof

Abstract

The invention discloses high-purity polyvinylidene fluoride resin as well as a preparation method and application thereof. According to the preparation method disclosed by the invention, no surfactant or an extremely low amount of surfactant is used, so that the prepared polyvinylidene fluoride resin is cleaner, and the requirements of piezoelectric material application on product quality and biocompatibility can be met; the method has the advantages of simple process operation, mild polymerization conditions, simplification of post-treatment demonomerization and water washing operations, and realization of stable and large-scale production of the high-purity polyvinylidene fluoride resin.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and in particular to a high-purity polyvinylidene fluoride resin and a preparation method and application thereof. Background Art

[0002] For the application of polyvinylidene fluoride resin in the fields of sensing, energy conversion and storage, wearable electronic devices, etc., in addition to the requirements for its own flexibility and electrical activity, there are also higher requirements for the cleanliness of the resin. High cleanliness means less impurities, which can avoid color changes, cracking problems and potential toxicity, and is conducive to improving product quality and biocompatibility.

[0003] At present, polyvinylidene fluoride and its copolymers are prepared based on suspension polymerization. The polymerization process is carried out above the critical conditions of the monomers. Dispersants, chain transfer agents and organic initiators are used in aqueous media to produce a slurry of coarse polymer particles with high product purity. However, the equipment requirements and technical barriers of suspension polymerization are relatively high. As we all know, monomers such as vinylidene fluoride, trifluoroethylene, and hexafluoropropylene are highly dangerous. The safety hazards caused by high pressure during suspension polymerization cannot be ignored. Therefore, limiting polymerization pressure has always been one of the goals pursued by safe production and large-scale production. In addition, different choices of reaction temperature, pressure, monomer dosage, dispersant and organic initiator will lead to different performances of copolymer products, and the residue of dispersant will also have a certain impact on the cleanliness of the product. Another important characteristic of polyvinylidene fluoride resin as a piezoelectric material is flexibility, but copolymers prepared by suspension polymerization often have high crystallinity, resulting in insufficient flexibility of the product.

[0004] Although the post-processing process of water-based emulsion polymerization is complicated, the surfactant is difficult to completely remove, and the product cleanliness is low, it has significant advantages such as fast polymerization rate, good system stability, mild reaction conditions and high product flexibility. Therefore, the development of a soap-free preparation process for polyvinylidene fluoride and its copolymers based on an aqueous emulsion polymerization method is of great significance for the stable and large-scale production of high-purity polyvinylidene fluoride resins. The soap-free mentioned here does not mean that no surfactant is used at all during the polymerization process, but that the amount of surfactant used is less than 0.01% of the total mass of the fluorinated monomer. However, at such a low surfactant content, it is extremely challenging to ensure the stability of the emulsion polymerization, so it is necessary to select a suitable polymerization formula and reaction device.

[0005] Chinese patent CN103755851 discloses a soap-free emulsion polymerization method of polyvinylidene fluoride, using fluorocarbon solvent as cosolvent, persulfate as initiator, and ester as molecular weight regulator. However, the preparation method needs to heat and recover the fluorocarbon solvent, and the initiator and regulator are both continuously fed. Chinese patent CN111148772 stabilizes polyvinylidene fluoride latex by RAFT emulsion polymerization in situ formed amphiphilic block copolymer based on PEG without adding any fluorinated surfactant. However, the preparation method needs to pre-synthesize hydrophilic polymer chains by controlled free radical polymerization, and even needs to chemically modify the pre-synthesized hydrophilic polymer chains. Although the soap-free emulsion polymerization method developed in the prior art has tried to reduce the use of surfactants, the additional auxiliary agents, cumbersome operations and pre-synthesis steps will increase production costs and process complexity. At present, it is still necessary to develop a low-cost, simple and efficient process based on soap-free emulsion polymerization to prepare polyvinylidene fluoride resin with high cleanliness. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, the embodiments of the present invention provide a high-purity polyvinylidene fluoride resin and a preparation method and application thereof. The present invention uses an appropriate amount of persulfate initiator and develops a soap-free emulsion polymerization preparation process with the aid of a supergravity reactor to obtain a high-purity polyvinylidene fluoride resin.

[0008] In a first aspect, the present invention provides a method for preparing a high-purity polyvinylidene fluoride resin, comprising the following steps:

[0009] (a) pumping deionized water containing a surfactant into a supergravity reactor and starting the reactor, and pumping a chain transfer agent solution into the reactor at one time after deoxygenation;

[0010] (b) after heating to the reaction temperature, pumping in the comonomer to the reaction pressure, and pumping in the persulfate initiator solution at one time to start the polymerization reaction, and maintaining a constant pressure;

[0011] (c) After the polymerization reaction is completed, the emulsion from which the unreacted monomers are removed is subjected to mechanical demulsification, washing, and drying to obtain polyvinylidene fluoride and its copolymer powders.

[0012] In step (a), deoxygenation can be achieved by introducing an inert gas, wherein the inert gas can be nitrogen or argon. In step (b), the pressure in the high gravity reactor is maintained constant by adding vinylidene fluoride and other monomers.

[0013] Furthermore, the amount of the surfactant is 0 to 0.01% of the total mass of the comonomer.

[0014] In some embodiments, the surfactant is used in an amount of 0 to 0.005% of the total mass of the comonomer.

[0015] The surfactant may be added or not. When the surfactant is added, the amount thereof may be 0.001%, 0.003%, 0.005%, 0.007%, 0.009%, 0.01% of the total mass of the comonomer or a value within a range consisting of any two values. The high shear force provided by the high gravity reactor of the present invention improves the stability of the polymerization system, reduces the amount of the surfactant, and the obtained polyvinylidene fluoride resin is cleaner.

[0016] Furthermore, the comonomer includes vinylidene fluoride and other monomers in a mass ratio of 40:60 to 90:10.

[0017] In some embodiments, the mass ratio of vinylidene fluoride to other monomers is 65:35 to 85:15. Too much or too little vinylidene fluoride is not conducive to improving the crystallinity of the polymer and the degree of orientation of the molecular chain, resulting in insignificant piezoelectric performance.

[0018] Furthermore, the surfactant includes one or more of a fluorine-containing surfactant and a non-fluorine-containing surfactant.

[0019] In some embodiments, the surfactant is a perfluoropolyether carboxylate, such as ammonium perfluoropolyether carboxylate, sodium ammonium perfluoropolyether carboxylate, and the like.

[0020] Furthermore, the persulfate initiator includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate. The persulfate initiator used in the present invention can generate negative ion free radicals by thermal decomposition in the water phase, which can not only initiate and promote free radical polymerization, but also form an active polymer chain with a hydrophilic group at one end having a surfactant effect. By adding a suitable amount of persulfate initiator, the stability of the polymerization system can be effectively maintained.

[0021] Furthermore, the amount of the persulfate initiator is 0.05%-0.2% of the total mass of the comonomer. Adding too much persulfate initiator will result in a very low molecular weight of the polymer and a wide molecular weight distribution; adding too little persulfate initiator will result in a slow polymerization reaction rate and fail to effectively maintain the stability of the soap-free emulsion polymerization system.

[0022] Further, the chain transfer agent includes one or more of acetone, isopropanol, cyclohexane, ethyl ether, methyl tert-butyl ether, ethyl acetate, methyl propionate, ethyl propionate, diethyl malonate, diethyl succinate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0023] Furthermore, the amount of the chain transfer agent is 0.15% to 3% of the total mass of the comonomer. Too much chain transfer agent will significantly reduce the molecular weight of the polymer; too little chain transfer agent will not effectively control the molecular weight and molecular weight distribution of the polymer and reduce polymer chain branching and crosslinking.

[0024] In soap-free emulsion polymerization, in order to ensure that the chain transfer agent and the initiator are evenly distributed in the reactor, it is often necessary to dilute the two to a certain concentration and adopt a continuous dropwise or batch feeding method, which increases the complexity of the preparation process to a certain extent. The present invention pumps the chain transfer agent and the initiator solution at one time, and uses supergravity technology to strengthen molecular mixing, which is conducive to the uniform distribution of initiator fragments, chain transfer agents, monomers and latex particles in the reactor, thereby simplifying the soap-free preparation process and improving product quality.

[0025] Furthermore, the high gravity reactor includes one or more of a high gravity rotating packed bed, a high gravity rotating spiral channel, a high gravity rotating disc, and a stator-rotor type high gravity rotating device.

[0026] Further, the hypergravity level of the hypergravity reactor is 15-700g, wherein g is the acceleration due to gravity. The hypergravity level of the hypergravity reactor can be 15g, 20g, 50g, 100g, 150g, 200g, 250g, 500g, 600g, 700g or a value within a range consisting of any two values.

[0027] In some embodiments, the hypergravity level of the hypergravity reactor is 50-500 g.

[0028] Furthermore, in step (b), the reaction temperature is 75-87° C., the reaction pressure is 2.1-3.0 MPa, and the polymerization reaction time is 1-2 h.

[0029] The polymerization reaction temperature can be 75°C, 80°C, 85°C, 87°C or a value within a range consisting of any two values. The present invention utilizes ultra-gravity technology to enhance heat transfer. Therefore, the reaction temperature does not need to be very high. At the same time, it is beneficial to control the temperature of the reaction system, prevent overheating to produce gel, and increase the solid content of the polymer particles.

[0030] The reaction pressure may be 2.1 MPa, 2.5 MPa, 3.0 MPa or a range consisting of any two of these values.

[0031] The polymerization reaction time can be 1 h, 1.5 h, 2 h or a value within a range consisting of any two values. The present invention utilizes ultra-gravity technology to enhance mass transfer, thereby increasing the polymerization rate and shortening the reaction time.

[0032] In some embodiments, the reaction temperature is 80-85°C.

[0033] In some embodiments, the reaction pressure is 2.2-2.6 MPa.

[0034] Furthermore, the remaining monomers include one or more of trifluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, chlorofluoroethylene, and tetrafluoroethylene.

[0035] The present invention utilizes ultra-gravity technology for strong mass transfer, thereby improving the problem of slow polymerization rate in the early stage of soap-free emulsion polymerization caused by poor water solubility of monomers such as vinylidene fluoride, trifluoroethylene, hexafluoropropylene, and chlorotrifluoroethylene.

[0036] Furthermore, in the step (c), the unreacted monomers are removed after the polymerization reaction is completed, the supergravity level of the supergravity reactor is increased by 20g and the temperature is started to be lowered, and the exhaust port of the supergravity reactor is opened to collect the unreacted monomers.

[0037] In some embodiments, the washing in step (c) comprises a water washing operation, and the mechanical demulsification product is repeatedly washed three times with deionized water.

[0038] In a second aspect, the present invention provides a high-purity polyvinylidene fluoride resin prepared by the method proposed in the first aspect of the present invention.

[0039] In a third aspect, the present invention provides applications of the high-purity polyvinylidene fluoride resin prepared by the method provided in the first aspect or the high-purity polyvinylidene fluoride resin provided in the second aspect in sensing, wearable electronic devices, energy conversion and storage.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] The invention utilizes a supergravity soap-free emulsion polymerization process to prepare polyvinylidene fluoride resin. The supergravity technology strengthens mass transfer and improves the polymerization rate in the early stage of soap-free emulsion polymerization. The strong shearing effect provided by the supergravity field is conducive to maintaining the stability of the emulsion and improves the stability of the soap-free emulsion polymerization system. An appropriate amount of persulfate initiator plays a certain emulsifying role after initiating the polymerization reaction. Under the conditions of enhanced molecular mixing and strong shearing effect of the supergravity field, the stability of the polymerization system is further improved.

[0042] The present invention does not use or uses a very low amount of surfactant, and the prepared polyvinylidene fluoride resin is cleaner and can meet the product quality and biocompatibility requirements of piezoelectric material applications.

[0043] The process of the invention has simple operation and mild polymerization conditions, simplifies post-processing monomer removal and water washing operations, and can realize stable and large-scale production of high-purity polyvinylidene fluoride resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0045] Figure 1 The process flow chart of the preparation method of high-purity polyvinylidene fluoride resin of the present invention;

[0046] Figure 2 This is a diagram of a preparation device for high-purity polyvinylidene fluoride resin of the present invention;

[0047] Description of reference numerals:

[0048] Chain transfer agent solution storage tank 1, vinylidene fluoride monomer storage tank 2, other monomer storage tanks 3, persulfate solution storage tank 4, supergravity reactor 5. DETAILED DESCRIPTION

[0049] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0050] The process flow and device for preparing the high-purity polyvinylidene fluoride resin of the present invention are as follows: Figure 1 and Figure 2 As shown, Figure 1 The process flow shown is not described here. Figure 2 As shown, the chain transfer agent is stored in a chain transfer agent solution storage tank 1, the vinylidene fluoride monomer is stored in a vinylidene fluoride monomer storage tank 2, the remaining comonomers are stored in a remaining monomer storage tank 3, the persulfate emulsion is stored in a persulfate storage tank 4, and the required materials are pumped into a gravity reactor 5 by a pressure pump.

[0051] The following is a detailed description with reference to the examples and comparative examples. Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0052] Example 1

[0053] 4000g of deionized water was pumped into the supergravity rotating packed bed reactor, and nitrogen was passed into the reactor for 30 minutes for deoxygenation. Then the air was evacuated, the supergravity level was adjusted to 100g, 100mL of 10wt% ethyl acetate solution was pumped in, the water feed in the reactor was heated to the required reaction temperature of 85°C, and vinylidene fluoride and trifluoroethylene monomers were added at a mass ratio of 70:30, and the reactor pressure was increased to 2.6MPa by the addition of monomers. After the reactor pressure stabilized, 200mL of 5wt% potassium persulfate solution was pumped in to initiate free radical polymerization. Subsequently, the pressure in the reactor was maintained constant by adding vinylidene fluoride and trifluoroethylene monomers until a total of about 1400g of vinylidene fluoride and a total of about 600g of trifluoroethylene were introduced into the reaction mass, and the feeding was stopped. After 2h, the polymerization reaction was terminated, the supergravity reactor was vented and the emulsion was collected, and the obtained emulsion was mechanically demulsified, washed, and dried to obtain vinylidene fluoride-trifluoroethylene copolymer powder.

[0054] Example 2

[0055] 4000g of deionized water was pumped into a supergravity rotating packed bed reactor, and nitrogen was passed into the reactor for 30 minutes for deoxygenation. Then, the gas was evacuated, the supergravity level was adjusted to 250g, 100mL of 10wt% ethyl acetate solution was pumped in, the water feed in the reactor was heated to the desired reaction temperature of 82°C, and vinylidene fluoride and trifluoroethylene monomers were added at a mass ratio of 82.5:17.5, and the reactor pressure was increased to 2.4MPa by the addition of monomers. After the reactor pressure stabilized, 200mL of 2wt% potassium persulfate solution was pumped in to initiate free radical polymerization. Subsequently, the pressure in the reactor was maintained constant by adding vinylidene fluoride and trifluoroethylene monomers until a total of about 1650g of vinylidene fluoride and a total of about 350g of trifluoroethylene were introduced into the reaction mass, and the feeding was stopped. After 1.5h, the polymerization reaction was terminated, the supergravity reactor was vented and the emulsion was collected, and the obtained emulsion was mechanically demulsified and dried to obtain vinylidene fluoride-trifluoroethylene copolymer powder.

[0056] Example 3

[0057] 0.1g of perfluoropolyether carboxylate is completely dissolved in 4000g of deionized water, pumped into a supergravity rotating packed bed reactor, and nitrogen is passed into the reactor for 30 minutes for deoxygenation. Then, the gas is evacuated, the supergravity level is adjusted to 100g, 100mL of 10wt% ethyl acetate solution is pumped in, the water feed in the reactor is heated to the desired reaction temperature of 84°C, and vinylidene fluoride and trifluoroethylene monomers are added at a mass ratio of 85:15. The reactor pressure is increased to 2.4MPa by the addition of monomers. After the reactor pressure is stable, 100mL of 2wt% potassium persulfate solution is pumped in to initiate free radical polymerization. Subsequently, the pressure in the reactor is maintained constant by adding vinylidene fluoride and trifluoroethylene monomers until a total of about 1700g of vinylidene fluoride and a total of about 300g of trifluoroethylene are introduced into the reaction mass, and the feed is stopped. After 1.5 hours, the polymerization reaction was terminated, the ultra-gravity reactor was vented and the emulsion was collected. The obtained emulsion was mechanically demulsified and dried to obtain vinylidene fluoride-trifluoroethylene copolymer powder.

[0058] Example 4

[0059] 4000g of deionized water was pumped into the supergravity rotating packed bed reactor, and nitrogen was passed into the reactor for 30 minutes for deoxygenation. Then the air was evacuated, the supergravity level was adjusted to 500g, 100mL of 5wt% ethyl acetate solution was pumped in, the water feed in the reactor was heated to the desired reaction temperature of 80°C, and vinylidene fluoride, trifluoroethylene and chlorotrifluoroethylene monomers were added in a mass ratio of 80:15:5, and the reactor pressure was increased to 2.6MPa by the addition of monomers. After the reactor pressure stabilized, 100mL of 1wt% potassium persulfate solution was pumped in to initiate free radical polymerization. Subsequently, the pressure in the reactor was maintained by adding vinylidene fluoride, trifluoroethylene and chlorotrifluoroethylene monomers until about a total of 1600g of vinylidene fluoride, about a total of 300g of trifluoroethylene and about a total of 100g of chlorotrifluoroethylene were introduced into the reaction mass, and the feeding was stopped. After 1 hour, the polymerization reaction was terminated, the ultra-gravity reactor was vented and the emulsion was collected. The obtained emulsion was mechanically demulsified and dried to obtain vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer powder.

[0060] Comparative Example 1

[0061] Dissolve 5g of perfluoropolyether carboxylate in 4000g of deionized water. After complete dissolution, pump it into a 5L vertical reactor and pass nitrogen into the reactor for 30 minutes for deoxygenation. Then evacuate the air, adjust the speed of the stirring paddle to 500rpm, heat the water feed in the reactor to the required reaction temperature of 85°C, start adding vinylidene fluoride and trifluoroethylene monomers at a mass ratio of 70:30, and increase the reactor pressure to 2.6MPa by adding the monomers. After the reactor pressure stabilizes, pump in 100mL of 10wt% ethyl acetate solution and 200mL of 2wt% diisopropyl peroxydicarbonate aqueous emulsion to initiate free radical polymerization. Subsequently, the pressure in the reactor is maintained constant by adding vinylidene fluoride and trifluoroethylene monomers until a total of about 1400g of vinylidene fluoride monomers and 600g of trifluoroethylene monomers are introduced into the reaction mass, and the feeding is stopped. After 4 hours, the polymerization reaction was terminated, the reactor was vented and the emulsion was collected. The obtained emulsion was subjected to mechanical demulsification, multiple water washings and drying to obtain vinylidene fluoride-trifluoroethylene copolymer powder.

[0062] Comparative Example 2

[0063] 2.5g of perfluoropolyether carboxylate was dissolved in 4000g of deionized water. After complete dissolution, it was pumped into a 5L vertical reactor and nitrogen was passed into the reactor for 30 minutes for deoxidation. Then the air was evacuated, the stirring blade speed was adjusted to 500rpm, the water feed in the reactor was heated to the required reaction temperature of 81°C, and vinylidene fluoride, trifluoroethylene and trifluorochloroethylene monomers were added in a mass ratio of 80:15:5. The reactor pressure was increased to 2.4MPa by the addition of monomers. After the reactor pressure stabilized, 100mL of 10wt% ethyl acetate solution and 200mL of 2wt% potassium persulfate aqueous solution were pumped in to initiate free radical polymerization. Subsequently, the pressure in the reactor was maintained constant by adding vinylidene fluoride, trifluoroethylene and trifluorochloroethylene monomers until a total of about 1600g of vinylidene fluoride monomer, 300g of trifluoroethylene monomer and 100g of trifluorochloroethylene monomer were introduced into the reaction mass, and the feeding was stopped.

[0064] After 3.5 hours, the polymerization reaction was terminated, the reactor was vented and the emulsion was collected. The obtained emulsion was subjected to mechanical demulsification, multiple water washings and drying to obtain vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer powder.

[0065] The samples prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were tested for impurity content and breakdown strength. The test results are shown in Table 1.

[0066] HNMR and LC-MS were used to test the impurity content in the product.

[0067] When used as a piezoelectric material, the PVDF film needs to be polarized by applying an electric field. The higher the voltage, the more complete the polarization. However, if the voltage is too high, the film will be broken down. Generally, the higher the purity of the resin, the higher the breakdown voltage. The purity of the resin can be indirectly reflected by the breakdown voltage.

[0068] The breakdown strength test process is as follows: weigh 9g of vinylidene fluoride copolymer and dissolve it in 51g of butanone. After it is completely dissolved, stand it for 5 hours to degas. Provide a glass substrate coated with a polymer wet film by doctor blade coating and immediately dry it. After drying, place the film in an oven at 140°C for annealing, and then obtain a piezoelectric film by plasma in-situ polarization. Use a breakdown voltage tester to test its breakdown voltage.

[0069] Table 1:

[0070]

[0071] As can be seen from Table 1, the impurity content of the vinylidene fluoride copolymers prepared by soap-free emulsion polymerization in an ultragravity reactor in Examples 1 to 4 is significantly lower than that of the copolymers prepared by emulsion polymerization in a vertical kettle and subjected to complex water washing in Comparative Examples 1 and 2, indicating that the polymer product obtained by the preparation method of the present invention has higher purity; in addition, compared with Comparative Examples 1 and 2, the breakdown voltage of the piezoelectric films prepared by the samples of Examples 1 to 4 is significantly improved, further indicating that the polymer product prepared by Examples 1 to 4 has higher purity.

[0072] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be for different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0074] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing high-purity polyvinylidene fluoride resin, characterized in that: The following steps are involved: (a) pumping deionized water containing a surfactant into a supergravity reactor and starting the reactor, and pumping a chain transfer agent solution into the reactor at one time after deoxygenation; (b) after heating to the reaction temperature, pumping in the comonomer to the reaction pressure, and pumping in the persulfate initiator solution at one time to start the polymerization reaction, and maintaining a constant pressure; (c) after the polymerization reaction is completed, the emulsion from which the unreacted monomers have been removed is subjected to mechanical demulsification, washing, and drying to obtain polyvinylidene fluoride and copolymer powders thereof, The amount of the surfactant used is 0 to 0.01% of the total mass of the comonomers, and the comonomers include vinylidene fluoride and other monomers in a mass ratio of 40:60 to 90:

10.

2. The method according to claim 1, characterized in that The surfactant includes one or more of a fluorine-containing surfactant and a non-fluorine-containing surfactant.

3. The method according to claim 1, characterized in that The persulfate initiator includes one or more of sodium persulfate, potassium persulfate, and ammonium persulfate. The amount of the persulfate initiator is 0.05% to 0.2% of the total mass of the comonomer.

4. The method according to claim 1, characterized in that The chain transfer agent includes one or more of acetone, isopropanol, cyclohexane, ether, methyl tert-butyl ether, ethyl acetate, methyl propionate, ethyl propionate, diethyl malonate, diethyl succinate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and the amount of the chain transfer agent is 0.15% to 3% of the total mass of the comonomer.

5. The method according to claim 1, characterized in that The supergravity reactor includes one or more of a supergravity rotating packed bed, a supergravity rotating spiral channel, a supergravity rotating disc, and a stator-rotor supergravity rotating device. The supergravity level of the supergravity reactor is 15 to 700g, wherein g is the acceleration of gravity.

6. The method according to claim 1, characterized in that In step (b), the reaction temperature is 75-87° C., the reaction pressure is 2.1-3.0 MPa, and the polymerization reaction time is 1-2 h.

7. The method according to claim 1, characterized in that The remaining monomers include one or more of trifluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, chlorofluoroethylene, and tetrafluoroethylene.

8. The method according to claim 1, characterized in that In the step (c), the unreacted monomers are removed by increasing the supergravity level of the supergravity reactor by 20 g after the polymerization reaction is completed, starting to cool down, and opening the exhaust port of the supergravity reactor to collect the unreacted monomers.

9. A high-purity polyvinylidene fluoride resin, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the high-purity polyvinylidene fluoride resin prepared by the method according to any one of claims 1 to 8 or the high-purity polyvinylidene fluoride resin according to claim 9 in sensing, wearable electronic devices, energy conversion and storage.

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