Patent ID: 7279522

Claim:
Method of providing a fluoropolymer dispersion comprising: providing a fluoropolymer dispersion comprising fluorinated surfactant having a molecular weight of less than 1000 g/mol or being free thereof; reducing the amount of said fluorinated surfactant in said dispersion if the amount thereof is more than 0.05% by weight based on the total weight of solids of the dispersion; upconcentrating the fluoropolymer dispersion in the presence of a non-ionic surfactant so as to increase the amount of fluoropolymer solids in said dispersion; and adding an anionic surfactant selected from fluorinated anionic surfactants having a molecular weight of at least 1000 g/mol, non-fluorinated anionic surfactants and mixtures thereof, to the fluoropolymer dispersion prior to or after upconcentrating said fluoropolymer dispersion, wherein said upconcentration is carried out using ultrafiltration or thermal upconcentration, to give a resulting dispersion.