GB742625A - Constant environment process for polymerizing ethylene - Google Patents

Abstract

<PICT:0742625/IV(a)/1> A continuous process for the polymerization of ethylene is conducted in an autoclave with turbulent end-over-end mixing at substantially constant super-atmospheric pressure and elevated temperature, with constant initiator concentration and a constant ratio of polymer to unreacted ethylene, preferably 0.05 to 0.50. A mixture of ethylene and initiator is introduced into the autoclave 1 through conduit 5. Stirrer 2 is started and the feed continued until the desired pressure is reached, which is regulated by opening conduit 6. The temperature is then raised by internal or external heaters until polymerization starts and the temperature rises. The amount of initiator is reduced, heating of the feed and/or reaction mixture is reduced and the rate of introduction of the reactants and of removal of polymer controlled to maintain constant conditions. Suitable initiators are hydrogen, benzoyl, lauroyl, ditertiary butyl, and diethyl peroxides, diethyl peroxydicarbonate, tetraethyl lead, aluminium hydroxide, triethyl aluminium, ethyl magnesium chloride and a ,a 1-azodiisobutyronitrile. The polymerization may be carried out in bulk or in cyclohexane alone or mixed with benzene. The products have a narrow molecular weight range and improved extrusion properties. Specifications 471,590, 579,894 and 626,155 are referred to.