Patent ID: 8598267

Claim:
Fluoropolymer dispersion comprising fluoropolymer particles having an average particle size of 10 to 400 nm dispersed in water, said dispersion being free of fluorinated surfactant having a molecular weight of less than 1000 g/mol or containing said fluorinated surfactant having a molecular weight of less than 1000 g/mol in an amount of not more than 0.025% by weight based on the total weight solids of said dispersion, said dispersion further comprising a non-ionic surfactant characterized in that said dispersion contains 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, wherein said dispersion comprises at least 30% by weight of the fluoropolymer particles based on the total weight of said dispersion because said dispersion is upconcentrated using ultrafiltration or thermal concentration, wherein the anionic surfactant is present in an amount of 100 to 3000 ppm based on the total weight of solids in the dispersion.