Process for removing fluorosurfactant from aqueous fluoropolymer dispersions and reducing scum formation

摘要

A process for reducing fluorosurfactant content of a stabilized fluorosurfactant-containing aqueous fluoropolymer dispersion containing ferric ions by contacting the fluoropolymer dispersion with strong base anion exchange resin to reduce fluorosurfactant content to a predetermined level, the anion exchange resin being in the hydroxide form, separating the dispersion from the anion exchange resin, and adding an effective amount of chelating agent having an equilibrium constant when complexed with iron of at least 10¹⁸ prior to the contacting with the ion exchange resin for complexing ferric ions to prevent scum formation.