Process for preparing fluoropolymer dispersions

Details Process for preparing fluoropolymer dispersions Process for preparing fluoropolymer dispersions

2007-11-20

2007-11-20

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C523S310000, C524S546000, C524S379000, C524S423000, C562S605000

Reexamination Certificate

active

10968048

ABSTRACT:
A process for preparing fluoropolymer dispersions, substantially free from anionic fluorinated surfactants, and with a coagulum amount <0.1% by weight, comprising:a) step a1) addition of:a non ionic surfactant having cloud point (CP) between 40° and 80° C., in an amount from 1.5% to 50% by weight on the dispersion fluoropolymer; andoptionally an electrolyte to bring the specific conductivity of the dispersion to values in the range 130-8,000 μS/cm;optionally a buffer agent to have a pH between 2 and 12to a fluoropolymer dispersion obtainable by an emulsion polymerization process;step a2):heating of the dispersion obtained in a1) up to a temperature Tcin the range CP±10° C.;decantation without stirring, at the temperature Tc, until obtaining the dispersion separation in two aqueous phases, of which the lower one containing the fluoropolymer is discharged;b) step b1):the dispersion obtained in step a2) is optionally additioned of an electrolyte and of a non ionic surfactant as in a1).

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