Production method of high-purity vinylidene fluoride monomers

Abstract

The invention relates to a production method of high-purity vinylidene fluoride monomers. In the purification process of vinylidene fluoride, heavy components and high-boiling residues are firstly removed, then light components are removed, finished products are produced in a tower kettle, and vinylidene fluoride monomers with the purity more than or equal to 99.999% are produced in the tower kettle without removing the heavy components for a second time, thus saving the investment in equipment and reducing the operating expense. Simultaneously, the finished products of the vinylidene fluoride are extracted by adopting the tower kettle in liquid phase, thus reducing the cold consumption when extracting the products.

Description

technical field [0001] The invention belongs to the field of preparation of fluorine-containing fine chemicals, and in particular relates to a production method of high-purity vinylidene fluoride monomer. Background technique [0002] Vinylidene fluoride (VDF) was first synthesized by F·Swarts in 1901 by reacting 1,1-di-fluoro-2-bromoethane (FC-142B) with sodium valerate. In 1946, DuPont of the United States used difluorodichloroethane to heat and dehydrochloride to obtain vinylidene fluoride monomer. Around the 1950s, major developed countries carried out research on various synthesis methods and product development based on fluororubber and polyvinylidene fluoride, and prepared vinylidene fluoride on a laboratory scale and an intermediate factory scale. In the 1960s and 1970s In the 1970s and 1980s, companies such as DuPont and Pennwlt in the United States established industrialized devices. In the 1970s and 1980s, the production technology became more and more mature, an...

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Problems solved by technology

[0008] (1) In the process of product purification, three rectification towers are used for deheavy components, light components and finished products respectively, which has the defects of waste of equipment investment and high operating cost

[0009] (2) The removal of light components such as acetylene only uses a light removal tower. Since the boiling point of acetylene and other impurities is close to that of vinylidene fluoride, a large amount of vinylidene fluoride is used to bring out light components in the process of removing light components. , there is a defect of high product consumption

[0010] (3) Although the purity of vinylidene fluoride has increased to 99.99%, there are still a small amount of impurities that cannot be removed, which affect the performance of the polymer

[0011] (4) In the above process, components with a boiling point between R-142b and vinylidene fluoride (such as vinylidene fluoride, etc.) are returned to the low-pressure system from the top of the vinylidene fluoride recovery tower, and so circulated. Over time, monofluoride The content of ethylene and other intermediate components in the system will increase day by day, which will increase the content of vinylidene fluoride in vinylidene fluoride. Properties of Vinylidene Fluoride Polymers

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