A method suitable for preparing fluoropolymers free of perfluorooctanoic acid or perfluorooctanoic acid

Abstract

The invention discloses a method suitable for preparing a fluorine-containing polymer without perfluorooctanoic acid or perfluorooctane sulfonic acid. The preparation method comprises: performing aqueous emulsion polymerization with one or more fluorinated monomers; During aqueous emulsion polymerization, polyfluoroalkoxy ether acid is used as emulsifier, the fluorine-containing polymer prepared by the present invention is free of perfluorooctanoic acid or perfluorooctane sulfonic acid, and the polyfluoroalkoxy ether acid is terminal Polyfluoroalkoxy ether acid emulsifier based on halogen or hydrogen. Its technical scheme mainly involves the following three improvements: (1) Selecting polyfluoroalkoxy ether acid and its salt to replace PFOA / PFOS as fluorine-containing emulsifier, which can be effectively applied to the aqueous emulsion of fluorinated monomers Polymerization reaction; (2) the prepared fluoropolymer does not contain perfluorooctanoic acid or perfluorooctane sulfonic acid, which meets environmental requirements; (3) conforms to cost accounting, and can greatly increase the unit cost of equipment without increasing production equipment and personnel. At the same time, it can also improve production indicators such as polymerization time and polymerization yield.

Description

technical field [0001] The invention relates to the field of synthesis of fluorine-containing polymers, in particular, it is a method suitable for preparing fluorine-containing polymers not containing perfluorooctanoic acid or perfluorooctylsulfonic acid. Background technique [0002] Fluoropolymer is a general term for alkane polymers in which some hydrogen atoms are replaced by fluorine atoms. It is also a special kind of polymer material, which can be polymerized by one or more fluorine-containing monomers under certain conditions. The fluorine-carbon bond with high bond energy in its structure and the shielding effect of fluorine atoms on the molecular chain make it have a series of excellent characteristics, such as: excellent chemical corrosion resistance, dielectric properties, weather resistance, non-stickiness, excellent Friction properties, etc. Of course, due to its excellent performance, fluoropolymers have become one of the indispensable materials in many fields...

AI Technical Summary

Problems solved by technology

[0005] From the content disclosed in the above patent documents, we can also know that the existing disclosed fluorine-containing emulsifiers are all effective. Although the toxicological characteristics of fluorine-containing emulsifiers have been solved, none of them involve the production Product characteristics such as rate and particle size, taking the above-mentioned invention patent CN101218264B as an example, in this patent document, the comparison data of polymerization time, average particle size, SSG (particle specific gravity of fluoropolymer) and solid content are given, except polymerization time In addition, the rest of the data did not fluctuate significantly. It can be seen that although the existing fluorinated emulsifiers that do not contain PFOA have solved the possible harm to the human body caused by the high stability and refractory properties of PFOA / PFOS, they have no effect on the entire production process. The efficiency has not been substantially improved. At the same time, since the fluorine-containing emulsifier involved in the above invention patent CN101218264B is perfluoropolyether, we know that perfluoropolyether is composed of -CF2-O-CF 2 - such ether chains Composition, all the H atoms in the molecule are replaced by F atoms. From the perspective of industrial production, there is no way to achieve large-scale production. It is necessary to add a monomer whose terminal halogen is not F in the preparation process. As a chain transfer agent, industrial production can only be realized, and the production process is relatively complicated. Based on the increasingly fierce competition in the existing market, we must find a new fluorine-containing emulsifier, which can not only replace the use of PFOA / PFOS, but also Based on product performance, long-term and effective economic benefits can be obtained

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