PROCESS FOR THE PRODUCTION OF POLYOLEFINS WITH BROAD MOLECULAR WEIGHT DISTRIBUTION

摘要

The present invention is directed to a propylene homo- or copolymer having a polydispersity index (Pl), determined according ISO 6721-1, of at least 7.0 Pa-1; and a tensile modulus, determined according to ISO 527-2, of at least 1600 MPa measured on a test specimen prepared by injection molding according to ISO 1873-2. The present invention is furthermore directed to a process for the production of polyolefins in one or more reactors, wherein in at least one reactor the process comprises the following steps (c) feeding one or more (co)monomers and hydrogen to said at least one reactor, whereby the hydrogen concentration in said at least one reactor is periodically varied; (d) preparing an olefin homo- or copolymer in the presence of an olefin polymerization catalyst; (e) withdrawing the olefin homo- or copolymer from said at least one reactor whereby the following relation (A) is fulfilled wherein PH is the time of one variation period in said at least one reactor; and t is the average residence time of the polymer in said at least one reactor.