GB951024A - Curable polyolefin compositions - Google Patents

Abstract

A curable polyolefin composition comprises (1) a polymer of ethylene, (2) a copolymer of isoprene and isobutylene and (3) a per-compound curing agent selected from the group consisting of 2-4-dimethyl-2-4-di-t-butyl peroxy hexane, dicumyl peroxide, di-t-butyl peroxide and t-butyl perbenzoate. Specified polymers of ethylene are the homopolymer and copolymers with the monomers propylene, 1-butene, 1-pentene, acrylic derivatives e.g. alkyl acrylates, styrene and vinyl acetate. Preferred proportions are 3-100 parts (2) to 100 parts (1) and from 0.1 to 15% of the curing agent of the combined weight of polymer and copolymer. Modifiers e.g. insulating blacks, conducting blacks, silicas, clays, calcium carbonate, halogenated flameproofing additives, antimony oxide, heat and light stabilizers, antioxidants, colouring pigments and lubricants may also be present. Specification 898,670 is disclaimed.ALSO:Compositions for coating or covering electric wires and cables comprise a mixture of (1) a polymer of ethylene, (2) a copolymer of isoprene and isobutylene, and (3) 2-4-dimethyl-2-4-di-t-butyl peroxy hexane, di-cumyl peroxide di-t-butyl peroxide or t-butyl perbenzoate (see Division C3). In an example, an electrical conductor is coated with a semi-conducting layer on which is superimposed an insulating layer and then an outer semi-conducting layer. The layers may be applied in an uncured state by taping or extruding and then simultaneously cured by heat. The inner layer comprises 100 parts ethylene polymer, 20 parts copolymer, 45 parts conducting black and 2 parts curing agent (dicumyl peroxide), the intermediate layer 100 polymer, 20 copolymer and 2 curing agent, while the outer layer is the same as the inner layer. Alternatively some layers may be precured and some cured in situ or each applied uncured but cured before application of the next layer. Specification 898,670 is disclaimed.