Improvements in Electrical Insulation for Wires and Cables

摘要

1,151,405. Polyolefin compositions. FUJIKURA CABLE WORKS Ltd. 9 June, 1967 [10 June, 1966], No. 26700/67. Heading C3P. [Also in Division H1] An insulation material for wires and cables consists of a vulcanized rubber composition of (a) ethylene-propylene rubber, e.g. an ethylenepropylene copolymer or terpolymer, (b) finely divided calcium carbonate, surface treated with a hydrophobic fatty acid or its salt and (c) at least one filler, chosen from heavy calcium carbonate and carbon black having a particle size of at least 100mÁ, the proportions of the constituents controlling the electrical characteristics of the insulation. These materials are compounded, together with a cross-linking agent e.g. dicumyl peroxide, a vulcanization accelerator e.g. quinone dioxime, a softener e.g. a naphthene hydrocarbon and an ageing resistor. The compounded rubber is coated on a conductor and vulcanized. The insulation may be applied directly to a conductor, or over a semi-conducting layer, and a further semiconducting layer, shielding tape and cable sheath may be provided. A layer of the ethylene-propylene rubber with a layer of another synthetic rubber composition gives a graded insulation.