Patent ID: 6028140
Filing Date: 2000-02-22
Classification: C08F

Abstract:
Homopolymers or copolymers obtained by a multistage continuous process for the polymerization of one or more olefins having the formula CH.sub.2 .dbd.CHR, in which R is hydrogen or R has from 1 to 10 carbon atoms and is an alkyl, cycloalkyl or aryl group, the process comprising:(A) a first stage of polymerization in which one or more of the olefins are polymerized, in one or more reactors, in the presence of a catalyst comprising the product of reaction between an alkyl-Al compound and a solid component in the form of spheroidal particles with a mean diameter of between 10 and 150 .mu.m, comprising a compound of a transition metal M.sup.I selected from the group consisting of Ti and V, not containing M-.pi. bonds, and a halide of Mg in active form, to produce an olefin homo or copolymer,(B) a treatment stage in which the product obtained in the first stage of polymerization (A) is:(a) brought into contact with a compound capable of deactivating the catalyst present in the stage (A); and thereafter(b) brought into contact with a compound of a transition metal M selected from the group consisting of Ti, Zr, V, or Hf containing at least one M-.pi. bond and optionally with an alkyl-Al compound;(C) a second stage of polymerization in which one or more of the olefins are polymerized, in one or more reactors, in the presence of the product obtained in treatment stage (B);and wherein the amount of olefin homo- or copolymer produced in the first stage polymerization (A) and treated in treatment stage (B) is between 10% and 90% by weight of the total amount of polymer produced in stages (A) and (C) combined.