| 摘要 |
Ethylene polymers of molecular weight greater than 100,000 are prepared by polymerizing ethylene in a substantially dry phase in the presence of granular or pulverulent mixtures comprising polyethylene and solid or liquid catalysts, effective for the polymerization of ethylene at pressures below 200 atmospheres gauge, at temperatures below the caking or sintering temperature of the mixtures, while continuously mechanically dividing and/or agitating the mixtures whereby the ethylene is intimately contacted therewith. The catalyst may be diethyl aluminium monochloride, preferably mixed with titanium tetrachloride and a C9-C11 aliphatic hydrocarbon fraction, and may be sprayed into the reactor as the polymerization proceeds. The reactors may be provided with stirring, kneading or grinding devices, and the mixture supported on cooled surfaces, or the polymerization may be effected in fluidized bed or suspensoid processes. The reaction may be effected continuously in one or more stages, the gases moving concurrently with or countercurrently to the mixture which may be comminuted between stages. The reaction may be started with gases poor in ethylene, e.g. tail gases, or in a liquid phase, a dry powder for use in the invention being obtained by filtering or centrifuging.
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