Method suitable for preparing fluorine-containing polymer free from perfluoro caprylic acid or perfluorooctane sulfonic acid

Abstract

The invention discloses a method suitable for preparing fluorine-containing polymer free from perfluorooctanoic acid or perfluorooctane sulfonate. The method comprises the following step: carrying out an aqueous emulsion polymerization on one or more fluorinated monomers by taking polyfluoroalkoxyl ether acid as an emulsifier, wherein the prepared fluorine-containing polymer is free from perfluorooctanoic acid or perfluorooctane sulfonate, and the polyfluoroalkoxyl ether acid is a polyfluoroalkoxyl ether acid emulsifier with halogen or hydrogen. The technical scheme mainly refers to the following three aspects in modification: (1) the method which selects polyfluoroalkoxyl ether acid or salt thereof to replace PFOA / PFOS as the fluorine-containing emulsifier can be effectively applied to aqueous emulsion polymerization of the fluorinated monomers; (2) the prepared fluorine-containing polymer is free from PFOA / PFOS so as to satisfy the environmental requirements; and (3) the method meets the cost accounting and can greatly improve the single-kettle output of the equipment without increasing the production equipment and personnel, and meanwhile, the method further can improve production indexes such as polymerization time and polymerization time productivity.

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...

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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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