Process for removing fluorosurfactant from aqueous fluoropolymer dispersions and reducing scum formation
AssigneeE.I. du Pont de Nemours and Company
InventorsDavid Johnson, Robert Cavanaugh
Life of this patent
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Abstract
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.
Claims7
A process for reducing fluorosurfactant content of a stabilized fluorosurfactant-containing aqueous fluoropolymer dispersion containing ferric ions comprising:
- contacting said fluorosurfactant-containing aqueous fluoropolymer dispersion with strong base anion exchange resin to reduce fluorosurfactant content to a predetermined level, said anion exchange resin being in the hydroxide form,
- separating said anion exchange resin from said dispersion after the fluorosurfactant content has been reduced;
- and
- adding an effective amount of chelating agent having an equilibrium constant when complexed with iron of at least 1018 prior to said contacting with said anion exchange resin for complexing ferric ions to prevent scum formation.
Dependencies are inferred from the claim text.