Core for a longitudinally waterproof cable, and a method for producing such a core

摘要

The surface (13) of the insulation (12) of a core (10) is coated with microminiature hollow bodies (20) which can expand at increased temperature and consist of plastics which form elastic walls. When a cable core assembly in which such cores (10) are twisted is filled with a hot wax-like substance, the hollow bodies (20) foam up and thus enlarge the proportion of the filling compound containing encapsulated gas, which is associated with a considerable reduction in the dielectric constant. <IMAGE>