Patent ID: 9255164
Filing Date: 2016-02-09
CPC Classification: C08F,C08K,C09D

Claim Text:
1. Process for polymerizing fluoromonomer to form a dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, comprising (a) providing an aqueous medium in said reactor, (b) adding said fluoromonomer to said reactor, (c) adding polymerization initiator to said aqueous medium, thereby kicking off said polymerizing of said fluoromonomer, said kicking off being indicated by a pressure drop in the reactor of at least 10 psi, and (d) metering hydrocarbon surfactant into said aqueous medium after said kicking off of said polymerization, wherein said metering of said hydrocarbon surfactant commences when the concentration of said fluoropolymer in said aqueous medium is at least 0.6 wt %, and wherein said metering of hydrocarbon surfactant into said aqueous medium is at a metering rate of at least 0.005 g/l-hr and provides an amount of hydrocarbon surfactant in the aqueous medium sufficient to stabilize the dispersion of fluoropolymer particles formed during polymerization, and wherein said aqueous medium comprises no more than 50 ppm of surfactant based on the weight of surfactant divided by the weight of water present in the reactor before said kicking off of said polymerizing of said fluoromonomer and no halogen-containing surfactant is added to said aqueous medium during or after said kicking off of said polymerization.