GB871828A - Process for polymerizing alpha-olefins - Google Patents

Abstract

Alpha-olefins are polymerized by contacting within a reactor an alpha-olefin having not more than 8 carbon atoms in a dispersion, in an anhydrous and oxygen-free inert liquid medium, of preformed particles of solid polymers of the olefin and a solid polymerization catalyst comprising a salt of a metal of Group IV(a), V(a) or VI(a) whish in a valence other than its highest valence state, together with an activator therefor under polymerization conditions of temperature and pressure, the preformed particles having been prepared by comminuting solid polymers of the olefin-containing active catalyst so as to expose active catalyst surface. The dispersion of particles may be prepared in the same or separate reactor by contacting the alpha-olefin with a dispersion of catalyst particles and an activator therefor in an inert liquid medium thus forming solid polymer and solid catalyst which are then comminuted, or in the case of same reactor, the particles may be removed, comminuted and returned. Specified olefins are ethylene, propylene, their mixtures butene-1, butadiene, isoprene, 3-methylbutene-1 and the hexenes, heptenes and octenes. Specified activators, which may also be used to reduce the metal compound to its lower valence, are aluminium trialkyls (preferred), other metal alkyls, metal hydrides, metal borohydrides and alkyl metal halides. Solvents for the reaction are saturated hydrocarbons.