Patent ID: 9701772
Date: 2017-07-11
CPC Classifications: C08F

Claim:
1. A process for the preparation of a 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 in the presence of a single site catalyst; and subsequently (II) in a gas polymerisation step polymerising propylene and optionally at least one C2-10 alpha olefin comonomer, in the presence of the 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, and being free from an external carrier.