GB965838A - Polyethylene resin - Google Patents

Abstract

A single or multi-stage process comprises polymerizing ethylene in an initial stage at 19,000-26,000 p.s.i. and 220-370 DEG F. in the presence of a chain transfer agent, a polymerization catalyst, a catalyst carrier and in the absence of other additives to produce a solid-gas phase of unreacted ethylene and solid polyethylene which is passed with agitation to the second zone where except for the temperature of 400-500 DEG F. the conditions are as in the first zone. Alternatively, the pressures and temperatures in both or one polymerization zone are 21,000-23,000 p.s.i. and 460-475 DEG F. The polyethylene has a melt index of 2-3 and a density of 0.920-0.924. The catalyst may be 0.001-5% t-butyl perbenzoate, dilauroyl peroxide, an azonitrile or oxygen. The catalyst carrier may be mineral oil and/or cyclohexane, kerosenes and benzene. The chain transfer agent may be cyclohexane. The polyethylene may be used for injection or blow moulding, e.g. to form shaped articles, e.g. bottles and closures for glass bottles.