GB961795A - Improvements in the production of crosslinked polyolefins - Google Patents

Abstract

Polyethylene, polypropylene and/or polybutene or a copolymer thereof is cross-linked by incorporating 0.1-20% of an ester of p-quinone dioxime or (except for polypropylene) of the dioxime itself as the only cross-linking agent and heating the mixture at a temperature and for a time sufficient to cause cross-linking. 1-80% of a filler, e.g. carbon black, calcium carbonate, silica, alumina, oxides, hydroxides, silicates or clay, may be mixed with the polyolefine before curing. The ester may be formed in situ from the dioxime and an aliphatic or aromatic carboxylic acid, anhydride and/or ester of such an acid, and may be the benzoate, acetate, maleate, propionate, butyrate, dodecenylsuccinate or laurate. Polyethylene may be crosslinked at above 175 DEG C., oxidized polyethylene of carbonyl content at least 0.05% at above 150 DEG C., polypropylene at above 225 DEG C. and a copolymer of ethylene and propylene at above 200 DEG C. The polymer may contain an antioxidant, e.g. 4-41-thiobis- (6t-butyl-m-cresol) or 2, 21-methylene-bis-(4-ethyl-6-t-butylphenol) and may be shaped at or not more than 20 DEG C. above, its melting point, e.g. 20-150 DEG C., before being cross-linked. The polymer may be used to form a pipe, wire, cable jacketing, film or tubing. Specification 471,590 is referred to.