Patent ID: 8519072

Claim:
A process for polymerizing fluoropolymer comprising: dispersing fluoropolyether acid or salt and fluorosurfactant in an aqueous medium to form an aqueous polymerization agent concentrate comprising dispersed fluoropolyether acid or salt and fluorosurfactant, said fluoropolyether acid or salt having a number average molecular weight of at least about 800 g/mol, said fluorosurfactant having the formula: [R 1 —O n -L-A − ]Y + wherein: R 1 is a linear or branched partially or fully fluorinated aliphatic group which may contain ether linkages; n is 1; L is a linear or branched alkylene group which may be nonfluorinated, partially fluorinated or fully fluorinated and which may contain ether linkages; A − is an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion, and phosphonate; and Y + is hydrogen, ammonium or alkali metal cation; with the proviso that the chain length of R 1 —O n -L- is not greater than 6 atoms; said aqueous polymerization agent concentrate adjusted to contain 1500 ppm±100 ppm dispersed fluoropolyether acid or salt having a haze of less than about 10%; adding said aqueous polymerization agent concentrate to an aqueous polymerization medium to provide dispersed fluoropolyether acid or salt and fluorosurfactant in said medium; and polymerizing at least one fluorinated monomer in said aqueous polymerization medium in the presence of initiator and said dispersed fluoropolyether acid or salt and said fluorosurfactant to form an aqueous dispersion of particles of fluoropolymer.