| 摘要 |
A process for the preparation of a propylene copolymer, preferably a heterophasic propylene copolymer, in a multistage polymerisation process in the presence of a single site catalyst, said process comprising:
(I) in a slurry polymerisation step, polymerising propylene and optionally at least one C2-10 alpha olefin comonomer; and subsequently
(II) in a gas polymerisation step polymerising propylene and optionally at least one C2-10 alpha olefin comonomer, in the presence of catalyst and polymer from step (I);
(III) in a second gas polymerisation step, polymerising propylene and at least one C2-10 alpha olefin comonomer in the presence of the catalyst and polymer from step (II);
wherein said catalyst comprises
(i) a metallocene complex of a group (IV) metal, said metallocene comprising at least two cyclopentadienyl type ligands;
(ii) a boron based cocatalyst; and
(iii) an aluminoxane cocatalyst;
said catalyst being in solid form, preferably in solid particulate form, and being free from an external carrier. |
