| 摘要 |
PURPOSE:To produce the titled powder having excellent stretchability and mechanical properties, by polymerizing tetrafluoroethylene in an aq. medium under specified conditions. CONSTITUTION:Tetrafluoroethylene is introduced into an aq. medium contg. a water-soluble polymn. initiator and a nontelogenic surfactant in a sufficient amount to stabilize colloidal polytetrafluoroethylene particles. The polymn. reaction is initiated at 55-120 deg.C. When 10-85wt% conversion of tetrafluoroethylene to polymer is achieved, 0.7-20ppm of a short-stop selected from an arom. hydroxy compd. an arom amine compd. and a quinone compd. is added to the aq. medium, said short-stop having a solubility of 2.5X10<-6>mol/l in water at 25 deg.C and having no re-initiating ability after chain transfer or addition to free radicals in the polymn. system. Total polymn. time is prolonged 13% or more as compared to the case where said short-stop is not added, and the polymn. is completed to obtain the titled powder which has an average particle size of 0.1-0.5mum and in which core part constituting 50wt% of whole particles has a specific gravity of 2.210 and the specific gravity of final produced particle is smaller than that of core part. |
