Patent ID: 9175115
Filing Date: 2015-11-03
Classification: C08F

Abstract:
1. Process for reducing thermally induced discoloration of melt-processible fluoropolymer resin, said fluoropolymer resin produced by polymerizing fluoromonomer in an aqueous medium to form aqueous fluoropolymer dispersion and isolating said fluoropolymer from said aqueous medium to obtain said fluoropolymer resin, wherein said aqueous fluoropolymer dispersion is polymerized in the presence of hydrocarbon surfactant which causes said thermally induced discoloration, wherein all of the monovalent substituents on the carbon atoms of said hydrocarbon surfactant are hydrogen, and wherein the fluoropolymer resin has an initial thermally induced discoloration value (L* i ) at least about 20 L units on the CIELAB color scale below the L* value of equivalent fluoropolymer resin of commercial quality manufactured using ammonium perfluorooctanoate fluorosurfactant, said process comprising: heating the fluoropolymer resin to a heating temperature in the range of about 160° C. to about 400° C., said fluoropolymer resin during said heating being under static conditions; and exposing the heated fluoropolymer resin to an oxygen source, wherein said exposing of said fluoropolymer resin to oxygen source is carried out with the fluoropolymer resin heated to said heating temperature, said heating temperature being above the melting point of the fluoropolymer.