| 摘要 |
A process for producing cross-linked olefin polymer extrudates comprises blending the polymer with a predetermined mixture of a minor proportion of a curing agent and a major proportion of a further curing agent, said curing agents decomposing at different temperatures, heating the blend at least to a temperature at which the curing agent present in minor proportion will decompose quickly but below that at which the further curing agent will decompose such that a controlled proportion of cross-linking occurs either prior to or during extrusion, extruding the partially cross-linked polymer at a temperature below that at which the further curing agent decomposes and heating the extrudate to the decomposition temperature of the further curing agent. The preferred polymer is polyethylene. Many suitable curing agents are listed including lauroyl, benzoyl, p-chlorobenzoyl, 2,4-dichlorobenzoyl and octanoyl peroxides as minor curing agents, and t. butyl perbenzoate, t. butyl peracetate, di-t. butyl diperphthalate, dicumyl peroxide, 2,2-bis (t. butylperoxy) butane and t. butyl cumyl peroxide as further curing agents. Fillers, e.g. silica and carbon black, and anti-oxidants, e.g. zinc mercaptobenzimidazole, 2,2,4 - trimethyl - 2 - dihydroquinoline and nickel dibutyl dithiocarbamate, may be present and the products may be used for insulating high-voltage cables.
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