| 摘要 |
PURPOSE:To secure sufficient mechanical strength and prevent dielectric constant from lowering due to a protective layer by extrusion-coating a conductor with foam insulator and disposing a solid layer around the foam insulator. CONSTITUTION:When a core wire 6 passes a cross head 5, the wire is coated with an inner layer of plastic containing foam material coming out of a first extruder 2 and simultaneously with an outer layer of plastic containing conductive filler or of conductive plastic coming out of a second extruder 1. The plastic of the inner layer forms foam 7 due to pressure change when the wire is extruded through a die 4 and, when cooled later, constitutes a plastic foam- insulated cable. As the conductive plastic, various plastic materials doped with electron donor or electron receiver, for example plastics of high conductivity with trans-type polyacetylene, polynaphthalene, etc., are used. |
