| abstract |
(a) magnesium halide, a titanium compound having at least one Ti-halogen bond and at least two electron donor compounds, one of which is present in an amount of 50 to 90 mole percent relative to the total amount of donor and is selected from succinate, the other Is selected from 1,3 diethers) in the presence of a catalyst system comprising a solid catalyst component having an average particle size in the range of 15 to 80 μm, (b) aluminum alkyl, and optionally (c) an external electron donor compound. A process for preparing a propylene polymer composition, comprising the following steps (i) to (iv): (i) contacting the catalyst components (a), (b) and optionally (c); (ii) prepolymerizing to form a polymer in an amount of about 0.1 to about 1000 g per gram of solid catalyst component (a); (iii) polymerizing propylene to produce a propylene (co) polymer that is at least 85% by weight insoluble in xylene at 25 ° C .; And (iv) in a subsequent step carried out in the gas phase, polymerizing a mixture of ethylene and α-olefin CH 2 = CHR, wherein R is a hydrocarbon radical having 1-10 carbon atoms, to produce the ethylene copolymer. . |