Preparation method of fluorine-containing polymer

Abstract

The invention discloses a preparation method of fluorine-containing polymer. The fluorine-containing polymer is obtained through the emulsion polymerization of fluorine-containing olefins monomer in the aqueous medium of fluorine-containing surfactant under the existence of initiator, wherein the weight percentage concentration of the fluorine-containing surfactant in the aqueous medium is 0.01-1%, the weight percentage concentration of the initiator in the aqueous medium is 0.001-1%, the reaction temperature is 10-120 DEG C and the pressure is 1-6.5MPa, and the reaction time is 3-15hours. The fluorine-containing surfactant satisfies a general formula shown in the specifications, wherein a is equal to 0 or 1; b is equal to 1 or 2; c is equal to 1, 2 or 3; d is equal to 1 or 2; X is C1, F or CF3; Y is H, F or CF3; and M is carboxylate or sulphonate. According to the method, perfluoro caprylic acid and derivatives thereof are not used in the method, so the method is environment-friendly; the preparation process can be conducted under wild temperature and pressure condition without affecting the reaction ratio of the polyreaction; and polymer powder with multiple grain sizes can be obtained, and thereby fluorine-containing polymer products at various grades can be prepared.

Description

technical field [0001] The invention relates to a preparation method of a fluorine-containing polymer, in particular to a preparation method of a fluorine-containing polymer not containing perfluorooctanoic acid and its salt. Background technique [0002] The emulsion polymerization method of fluorine-containing olefins and copolymerized modified monomers has the advantages of fast polymerization rate, good copolymerization performance, small particle size in the resulting dispersion, high polymerization yield, and good dispersion stability. , is a more commonly used polymerization method for polymerizing fluoromonomers into fluoropolymers. Perfluorooctanoic acid and its salts (PFOA) are the most commonly used fluorosurfactants in the emulsion polymerization of fluoromonomers. However, because of their potential bioaccumulation, toxicity and regional diffusion, they have been approved by Switzerland, the European Union and the United States successively. etc. Restricted use...

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Problems solved by technology

[0003] DuPont uses the perfluoroalkyl iodide telomerization method to prepare various surfactants containing hydrocarbon segments in the molecular chain. As a substitute for PFOA, the preparation process is complicated and dangerous. It is used for fluorine-containing During the preparation method of polymer emulsion, the hydrocarbon segment in the molecular segment has the possibility of chain transfer phenomenon, which affects the polymerization process and polymer performance; 3M company adopts acyl fluoride telomerization method and perfluoroalkyl vinyl ether Raw materials are used to prepare surfactants containing ether bond segments in a variety of molecular chains. As a substitute for PFOA, they are used in the preparation method of fluoropolymer emulsions to prepare a variety of fluoropolymers, but this type of surfactants The raw materials used in the preparation are expensive and costly, and it is difficult to promote industrialization; the domestic Chenguang Chemical Research Institute has released a surfactant containing ether segments prepared by oxidizing fluorine-containing olefins with oxygen. As a substitute for PFOA, it is used for fluorine-containing In the preparation method of polymer emulsion, it does not affect the polymerization process, and the effect is better, but this kind of surfactant also has the problem of high risk in the preparation process

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