Process for producing an elastomer containing fluorine

A rubber like elastomer containing fluorine can be produced economically by irradiation of hexafluoropropane and vinylidene fluoride and/or tetrafluoroethylene with ionizing radiations at low temperatures, i.e., 1-450C. The proportion of hexafluoropropane, vinylidene fluoride and tetrafluoroethylene are within the range of the four points 8:92:0, 34:66:0, 42:28:30 and 16:54:30, preferably within 12:88:0, 30:70:0, 37:38:25 and 19:56:25 in mole ratio. The above copolymer can contain 0.01-10 mole%, preferably 0.5-5 mole%, of other monomers such as (meth)acrylic acid and esters, acetylene, ethylene and their halogene substitutes, vinyl compounds and derivatives. For irradiation, a Van de Graaf electron beam accelerator may be used with a total dose of 1 x 102 - 2 x 103 rad/hour. The temperature of polymerization is 1-450C but preferably 10-400C. The pressure of polymerization is 1-30kg/cm2 but 1-15kg/cm2 in the presence of halogenated hydrocarbon. In one example, 1,000cc of 1,1,2-trichlor-1,2,2-trifluoroethane were absorbed in a 3 liter stainless steel autoclave. This autoclave was charged with 750g of a mixed monomer of 50.6 hexafluoropropane, 44.9 vinylidene fluoride and 4.5 tetrafluoroethane in mole ratio. This charge was polymerized with Co-60 gamma-rays at a dose rate of 1 x 104 rad/hour at 300 while stirring. On the other hand, another 20 liter stainless steel autoclave connected to the above autoclave was filled with hexafluoropropane, vinylidene fluoride and tetrafluoroethylene (20:68:12) so as to maintain a constant pressure of polymerization at 10kg/cm2G. (Iwakiri, K.)