GB860363A - Improvements in or relating to the low pressure catalytic polymerisation of olefinic - Google Patents

Abstract

Polymers of olefinically unsaturated hydrocarbons are made by polymerizing the compound in the presence of a catalyst consisting of a component (A) and component (B) as later explained, in a plurality of stages in which the polymerization in the first stage is effected using a high concentration of the catalyst, i.e. a concentration of more than 20 millimols per litre of (A), and at least one subsequent stage in which the reaction medium withdrawn from the first stage is fed with additional hydrocarbon and further polymerization is effected using a conventional catalyst concentration, i.e. less than 20 millimols per litre of (A). The (A) component of the catalyst is a transition metal compound wherein the metal is in a lower than normal valency state and is preferably a compound of Group IVa, Va, VIa, VIIa or VIII of the Periodic Table, and the (B) component a metal, hydride, or organo-metallic compound of Group I, II, or III, or tin, or lead, or an organic boron compound or addition complex thereof. The polymerization is preferably effected in the liquid phase, but the first stage may be carried out in the gaseous phase and subsequent stages in the liquid phase or the entire polymerization may be effected in the gaseous phase. The gaseous phase polymerization is effected by vaporizing the catalyst components. When the first stage polymerization is effected in the liquid phase, a relatively viscous liquid medium is preferred, e.g. by adding a thickener or stabilizer such as polyisobutylene, to the solvent which may be isooctane. The olefinic monomer may be ethylene, propylene, n-butylene, or mixtures, or styrene. The monomer may be admixed with diluents such as ethane. The exemplified catalyst is titanium tetrachloride ((A) component), and aluminium diethyl monochloride ((B) component). The process may be operated continuously or batchwise and the ingredients utilized may be added portionwise. Specifications 799,332, 799,823, 801,031, 810,023, 819,867, 820,263, 837,064 and 840,859 are referred to.