Method for preparing fluorine-containing polymer by dispersion process

Abstract

The invention relates to a method for preparing a fluorine-containing polymer by a dispersion process, which comprises the following steps: carrying out polymerization reaction on a fluorine-containing monomer in the presence of an emulsifier and an initiator in a water phase system at 50-150 DEG C under the reaction pressure of 0.3-7 MPa, and after the reaction finishes, carrying out aggregation separation, water washing and drying on the fluorine-containing polymer in the reaction emulsion to obtain the solid fluorine-containing polymer; or concentrating the reaction emulsion until the concentration of the fluorine-containing polymer in the concentrated solution is 30-70 wt% to obtain the fluorine-containing polymer concentrated solution, wherein the emulsifier accounts for 0.01-2.0 wt% of the water in the reaction system in the polymerization process. By adopting the emulsifier, the fluorine-containing polymer, which has excellent properties and lower toxicity than the prior art, can be obtained, and the service performance and biological toxicity have the optimal balance.

Description

technical field [0001] The invention relates to a method for preparing a fluorine-containing polymer by a dispersion method, and belongs to the technical field of fluorine chemical industry. Background technique [0002] The most widely used fluorosurfactant in the field of dispersion production of fluoropolymers is perfluorooctanoic acid, namely C 7 f 15 COOH and its derivatives, or "C8", are synthetic rather than naturally occurring industrial raw materials. While the molecular structure of PFOA endows it with excellent surface properties, it is also doomed to its persistence and accumulation in the environment. Because PFOA molecules contain perfluorinated groups and the carbon chains connected to each other are relatively long, PFOA has strong thermal stability and dynamic stability, which increases the persistence of PFOA molecules in the environment. Studies have shown that PFOA is difficult to degrade under strong heat, light, chemical action, microbial action and ...

AI Technical Summary

Problems solved by technology

For example: Chenguang Chemical Industry Research Institute mentioned in Chinese patent document CN101648122A (application number 200910092202.2) that fluorine-containing olefins were oxidized by oxygen at low temperature to prepare ether-containing surfactants. The surfactants obtained by this method contained a large amount of Branched chain, poor dispersion during polymerization

In the Chinese patent document CN102504063A (Application No. 201110338501), Juhua Group uses a surfactant with a fluorine-containing ether segment containing chlorine atoms. This surfactant is highly toxic and cannot fully meet the requirements of environmental friendliness.

The surfactants mentioned in U.S. Patent Nos. 5,789,508, 4,025,709, 5,688,884, and 5,763,552, etc., will affect the product quality of the polymer during the polymerization process due to the relationship between the molecular structure