Patent ID: 9376520
Filing Date: 2016-06-28
CPC Classification: C08F,C08J

Claim Text:
1. A process for producing a polytetrafluoroethylene aqueous emulsion, the process comprising: charging to a polymerization reactor a full amount of at least one comonomer selected from the group consisting of CH adding to the reactor at least one fluorinated emulsifier selected from the group consisting of a C initiating an emulsion polymerization reaction of tetrafluorethylene in the presence of the at least one fluorinated emulsifier and the full amount of the at least one comonomer; and continuing the emulsion polymerization of tetrafluoroethylene to obtain an aqueous emulsion containing polytetrafluoroethylene microparticles having an average primary particle size of from 0.21 to 0.27 μm; wherein a stability time of an aqueous 20% solid content emulsion of the polytetrafluoroethylene microparticles at 23° C. is greater than 200 seconds, a content of the at least one comonomer in the polytetrafluoroethylene produced is from 0.0015 to 0.01 mass % relative to the final amount of polytetrafluoroethylene produced, and a stress relaxation time of the polytetrafluoroethylene produced is at least 500 seconds.