US Patent 7101925 Process for preparing fluoropolymer dispersions

A process to substantially remove the fluorinated anionic surfactants comprising the following steps:a) addition to a fluoropolymer dispersion of a nonionic surfactant, in an amount in the range 1.5%–25% by weight, referred to the fluoropolymer weight;b) addition to the dispersion of a salt, soluble in water and not giving precipitates in the dispersion under the use conditions;c) contact of the dispersion with a basic anionic exchanger;d) separation of the dispersion from the basic anionic exchanger;before step d) the dispersion being filterable on a 180 micrometer net and successively on a 10 micrometer net.