A preparation method of polyvinylidene fluoride and the prepared polyvinylidene fluoride and application thereof

Abstract

The present invention relates to the field of polymer technology, and more particularly to a method for preparing polyvinylidene fluoride and polyvinylidene fluoride prepared therefrom and its application, wherein the preparation method comprises the following steps: S1, adding a solvent, liquid paraffin oil and an initiator to a reactor, and cooling to ‑10~‑20°C; S2, introducing an inert gas into the reactor to replace air, and then introducing VDF to replace the inert gas; S3, introducing VDF into the reactor, and polymerizing at a temperature of 50~60°C and a pressure of 100~1000pis; S4, after the reaction is completed, cooling to room temperature, and obtaining polyvinylidene fluoride after suction filtration, washing and drying. The preparation method of the present invention does not require the use of a perfluorocarbon surfactant, and is environmentally friendly; the preparation process does not use deionized water, does not produce no waste water, and the solvent can be recycled and reused; the preparation process does not require emulsification, and does not require demulsification, and the process is simple and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of polymers, and in particular to a method for preparing polyvinylidene fluoride, the prepared polyvinylidene fluoride and applications thereof. Background Art

[0002] Polyvinylidene fluoride (PVDF) is a highly non-reactive thermoplastic fluorinated polymer with excellent chemical stability, thermal stability, mechanical stability and weather resistance. It is widely used in the chemical industry, biomedicine, construction, textile printing and dyeing, new energy, electronics, etc., and has become one of the indispensable high-performance materials in various fields.

[0003] Polyvinylidene fluoride can be synthesized by homopolymerization of vinylidene fluoride (VDF) monomers, or by copolymerization of vinylidene fluoride with other small amounts of fluorine-containing vinyl monomers. Currently, polyvinylidene fluoride polymerization requires the use of perfluorocarbon surfactants, such as perfluoro and polyfluoroalkyl substances (PFAS), which are a diverse group of man-made chemicals. However, PFAS are not easy to decompose, and some types have been shown to accumulate in the environment and in people's bodies. Exposure to certain types of PFAS may have serious health effects and cause permanent environmental pollution.

[0004] Therefore, it is particularly important to develop a method for preparing polyvinylidene fluoride without using perfluorocarbon surfactants. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing polyvinylidene fluoride, the prepared polyvinylidene fluoride and its application. The preparation method does not require the use of a perfluorocarbon surfactant, thus greatly reducing the pollution to the environment.

[0006] A first aspect of the present invention provides a method for preparing polyvinylidene fluoride, comprising the following steps:

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

[0008] S2, introducing inert gas into the reactor to replace air, and then introducing VDF to replace the inert gas;

[0009] S3, VDF is introduced into the reactor, and a polymerization reaction occurs at a temperature of 50-60°C and a pressure of 100-1000 pis (preferably 800-1000 pis);

[0010] S4. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain polyvinylidene fluoride.

[0011] Preferably, the initiator is a peroxide.

[0012] Preferably, the initiator includes any one of IPP (isoprene pyrophosphate) and TAPP (tetraaminophenylporphyrin).

[0013] Preferably, the solvent is dimethyl carbonate or F5058 fluorocarbon solvent.

[0014] Preferably, the usage ratio of VDF to dimethyl carbonate in step S3 is (160-200 g):(500-700 ml), more preferably 180 g:600 ml.

[0015] Preferably, in step S3, the mass ratio of VDF to F5058 fluorocarbon solvent is (180-200):(700-900), more preferably 210:800.

[0016] Preferably, in step S3, the mass ratio of VDF to liquid paraffin oil and initiator is (180-210):1:(1.4-1.5).

[0017] Preferably, the inert gas is nitrogen.

[0018] 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 VDF to a pressure of 40 to 60 pis, and repeat several times (preferably five times).

[0019] The second aspect of the present invention provides polyvinylidene fluoride prepared by the above-mentioned method for preparing polyvinylidene fluoride.

[0020] The third aspect of the present invention provides a use of the above-mentioned polyvinylidene fluoride in the preparation of lithium ion battery electrode materials.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention does not require the use of perfluorocarbon surfactants and is environmentally friendly;

[0023] (2) The preparation process of the present invention does not use deionized water, does not generate any wastewater, and the solvent can be recycled and reused;

[0024] (3) 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

[0025] 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.

[0026] Figure 1 The polyvinylidene fluoride prepared in Example 1 of the present invention;

[0027] Figure 2 The polyvinylidene fluoride prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Example 1

[0032] This embodiment provides a method for preparing polyvinylidene fluoride, comprising the following steps:

[0033] Put 600ml of analytically pure dimethyl carbonate, 1g of liquid paraffin oil, and 1.5g of IPP into a polymerization reactor, cover the reactor, cool to -15°C, replace the air with high-purity nitrogen five times (use a mechanical pump to draw out the gas in the reactor, introduce high-purity nitrogen to a pressure of 50pis, and repeat five times), and then replace the nitrogen with VDF five times in the same way, stir at 700 rpm, add 180g of VDF, heat to 50°C, pressure 868pis, start polymerization, maintain the temperature at 50-60°C, and the pressure gradually decreases. After 6 hours, the pressure drops to less than 100pis, stop keeping warm, cool to room temperature, open the lid after venting, filter, wash with 200ml of dimethyl carbonate, and bake at 60°C for 24 hours to obtain 148g of polyvinylidene fluoride.

[0034] The polyvinylidene fluoride prepared in this example is shown in Figure 1 .

[0035] Example 2

[0036] Into the polymerization reactor, 800g of 3M F5058 fluorocarbon solvent, 1g of liquid paraffin oil, and 1.4g of IPP were added, the reactor lid was covered, and the reaction mixture was cooled to -15°C. The air was replaced with high-purity nitrogen five times (the gas in the reactor 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 manner, the stirring speed was 700 rpm, 210g of VDF was added, the reaction mixture was heated to 48°C and the pressure was 968pis. The polymerization was started, the temperature was maintained at 50-60°C, and the pressure gradually decreased. After 6 hours, the pressure dropped to less than 100pis, and the insulation was stopped. The reaction mixture was naturally cooled to 36°C, cooled to room temperature with water, the lid was opened after venting, suction filtered, washed with 200g of F5058 fluorocarbon solvent, and dried at 60°C for 24 hours to obtain 178g of polyvinylidene fluoride.

[0037] The polyvinylidene fluoride prepared in this example is shown in Figure 2 .

[0038] Example 3

[0039] The polyvinylidene fluoride prepared in Example 1-2 is used in the preparation of lithium-ion batteries.

[0040] 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 polyvinylidene fluoride, characterized in that: The following steps are involved: S1. Add solvent, liquid paraffin oil and initiator into a reaction kettle and cool to -10 to -20°C; the solvent is dimethyl carbonate or F5058 fluorocarbon solvent; S2, introducing inert gas into the reactor to replace air, and then introducing VDF to replace the inert gas; S3, VDF is introduced into the reactor, and a polymerization reaction occurs at a temperature of 50-60°C and a pressure of 100-1000 pis; the mass ratio of VDF to liquid paraffin oil and initiator is (180-210):1:(1.4-1.5); the amount ratio of VDF to dimethyl carbonate is (160-200g):(500-700ml); the mass ratio of VDF to F5058 fluorocarbon solvent is (180-220):(700-900); S4. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain polyvinylidene fluoride.

2. The method for preparing polyvinylidene fluoride according to claim 1, characterized in that: The initiator is a peroxide.

3. The method for preparing polyvinylidene fluoride according to claim 2, characterized in that: The initiator includes: any one of IPP and TAPP.

4. The method for preparing polyvinylidene fluoride according to claim 1, characterized in that: The inert gas is nitrogen.

5. The polyvinylidene fluoride prepared according to the method for preparing polyvinylidene fluoride according to any one of claims 1 to 4.

6. Use of the polyvinylidene fluoride according to claim 5 in preparing electrode materials for lithium ion batteries.

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