Vinylidene fluoride → Hfp tfe

Beteiligte Stoffe

Reaktionsschritte

A VF2/HFP/TFE copolymer fluoroelastomer was prepared by a continuous emulsion polymerization process, carried out at 115° C. in a well-stirred 2.0-liter stainless steel liquid full reaction vessel. An aqueous solution, consisting of 2.09 g/hour (g/h) ammonium persulfate initiator, 0.84 g/h sodium hydroxide, 1.80 g/h sodium octyl sulfonate, and 1.01 g/h isopropanol chain transfer agent in deionized water, was fed to the reactor at a rate of 5.0 L/hour. The reactor was maintained at a liquid-full level at a pressure of 6.2 MPa by means of a backpressure control valve in the effluent line. After 30 minutes, polymerization was initiated by introduction of a gaseous monomer mixture consisting of 730 g/h vinylidene fluoride (VF2), 384 g/h hexafluoropropylene (HFP), and 130 g/h tetrafluoroethylene (TFE) fed through a diaphragm compressor. After 2.0 hours, collection of effluent dispersion was begun and collection continued for 6 hours. The effluent polymer latex, which had a pH of 4.52 and contained 20.12 wt. % solids, was separated from residual monomers in a degassing vessel at atmospheric pressure.

Herkunft & Nachweise