| 摘要 |
PURPOSE:To obtain an optical fiber cable causing almost no increase of light transmission loss by covering an external periphery of a strand of an optical fiber by extruding a molten specified copolymer of fluorine-contg. resin with an appropriate reduction drawing ratio, and cooling slowly thereafter. CONSTITUTION:An external periphery of an optical fiber strand comprising one or plural numbers of elemental wire is coated with a molten tetrafluoroethylene/perfluoroalkyl vinylether copolymer (PFA) by extruding with 60-120 reduction drawing ratio. Then, the coated elemental wire is cooled slowly in the air, etc. until the coated layer attains <=ca.100 deg.C. Said reduction drawing ratio is a value obtd. by dividing a bore size of a forming die with a finished wire size. Since, by this method, the contraction by the forming in the stage of extrusion coating with PFA is retarded to the least value, an optical fiber cable having reliability in the coating loss characteristics is obtd. |
