Process for preparing fluoropolymer dispersions

Abstract

A process to substantially remove fluorinated anionic surfactants from fluoropolymer dispersions comprising the following steps: a) addition to the fluoropolymer dispersion of one or more non fluorinated surfactants; b) contact of the dispersion with an anionic exchanger; c) separation of the dispersion from the anionic exchanger and recovery of the dispersion substantially fluorinated anionic surfactant free.

Description

technical field

[0001] The present invention relates to a process for the preparation of aqueous dispersions of fluoropolymers which are substantially free of fluorinated surfactants, in particular free of fluorinated ionic surfactants.

[0002] More particularly the present invention relates to a process for the preparation of aqueous fluoropolymer dispersions substantially free of perfluorooctanoate in acid or salt form. Background technique

[0003] By an aqueous fluoropolymer dispersion substantially free of fluorinated anionic surfactant is meant that the fluorinated surfactant content is less than 100 ppm, especially less than 50 ppm, more especially less than 5 ppm, based on the weight of the fluoropolymer.

[0004] Two different polymerization processes for the production of fluorinated polymers are known in the prior art: suspension polymerization and emulsion polymerization. Polymer particles with millimeter dimensions are obtained in the suspension polymerization...