PROCESS FOR THE PREPARATION OF POLYPROPYLENE-b-POLY(ETHYLENE-co-PROPYLENE)

摘要

A process for preparing polypropylene-b-poly-(ethylene-co-propylene) by the use of a tubular in-line polymerizer in the presence of an olefin-polymerizing catalyst comprising a solid catalyst component (1) composed of titanium, halogen and if necessary magnesium, an organometallic compound (2), and if necessary at least one electron-donating compound (3) selected from the group consisting of organosilicon compounds represented by the general formula: RnSi(OR')4-n (wherein R and R' are each independently a C1-C10 hydrocarbon group; and n is an integer of 1 to 3) and nitrogenous heterocyclic compounds, wherein the solid catalyst component (1) is preliminarily brought into contact with the organometallic compound (2) in the presence of the electron-donating compound (3), and then a polypropylene segment is formed through polymerization, immediately followed by the formation of a poly(ethylene-co-propylene) segment at the end of the polypropylene segment through polymerization. The process makes it possible to prepare the polymer efficiently with a reduced content of inorganic contaminants, even when the polymer is one having a weight-average molecular weight of as high as 100,000 or above.