Preparation method of polyvinylidene fluoride (PVDF)

Abstract

The invention belongs to the technical field of organic synthesis and particularly relates to a preparation method of PVDF. Vinyl fluoride, deionized water, initial chain transfer agents and a dispersing agent are added to a reaction kettle, evacuation and deoxygenization are performed, the temperature is raised to 20 DEG C to 150 DEG C, the kettle is refilled with vinylidene fluoride monomers until the pressure in the kettle is 1.0-6.0 MPa, and an initial chain transfer agent is added; polymerization reaction is started, the kettle is refilled with another chain transfer agent and a replenishing initiator, and after the reaction, the finished product is obtained after the obtained polymer emulsion is subjected to condensation, washing, drying and granulation. According to the preparation method of the PVDF, two kinds of chain transfer agents are firstly used in the polymerization process, a production technology of the PVDF with controllable molecular weight and distribution of the molecular weight for narrow size distribution is provided, and the technological conditions are mild and easy to control; the molecular weight of the product obtained by polymerization is uniform, the distribution is narrow, and the production efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of polyvinylidene fluoride. Background technique [0002] Polyvinylidene fluoride (PVDF) is a fluorine-containing thermoplastic engineering plastic with chemical corrosion resistance, aging resistance and excellent mechanical processing properties. It is processed into various products through extrusion, injection, molding and other molding processes. It is widely used In the manufacturing industry, electronics industry and water treatment industry and other fields. [0003] In view of the increasingly widespread application of PVDF, people's demand for PVDF is increasing, and the attention paid to the yield of PVDF is getting higher and higher; in addition, in terms of product performance, especially in the molding process, uneven heating, Wide molecular weight distribution and easy decomposition of small molecular substances will caus...

AI Technical Summary

Problems solved by technology

[0009] In addition, the patent FR2259114 uses acetone as the chain transfer agent, the patent US4360652 uses isopropanol as the chain transfer agent, and CN101218264B uses dimethyl ether, halogenated hydrocarbons and alkanes as the chain transfer agent, but the PVDF obtained by using these chain transfer agents still has a wide range. Molecular weight distribution, its molecular weight distribution coefficient is usually between 4-20

A large amount of high molecular weight components leads to processing difficulties, and a large amount of low molecular weight components leads to yellowing of products and reduced mechanical properties and chemical resistance

[0010] And from the content disclosed in the above patent documents, we can also know that none of the documents involve product characteristics such as polymerization time, yield, and particle size of polyvinylidene fluoride; even in CN101218264B, a comparison of polymerization time, average particle size, and solid content is given. data, but except for the aggregation time, the rest of the data have not improved significantly, so it can be seen that the existing technology has not made any substantial improvement to the overall production efficiency

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