| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject copolymer excellent in extrusion processability, capable of allowing a uniform orientation processing and excellent in heat stability and strength by copolymerizing tetrafluoroethylene with a specific fluorinated comonomer. SOLUTION: The objective copolymer is obtained by copolymerizing tetrafluoroethylene with a fluorinated comonomer of the formula [(m) is 0-2; (n) is 1-3], [e.g. perfluoro(1,4-butanediol divinyl ether)]. The containing proportion of the polymerization unit based on the fluorinated comonomer is 0-0.5 mol.%. The standard specific gravity of the copolymer is preferably <2.155. The copolymer is obtained by an emulsion polymerization, by loading water, a free radical polymerization initiator, a disperse-stabilizer (e.g. a paraffin wax and a solvent) and an emulsifier, preferably successively adding or halfway- separately adding the tetrafluoroethylene, adding the fluorinated comonomer at once at the initial time, and polymerizing the loaded and added materials at 50-120 deg.C under 6-40 kg/cm<2> pressure. |
