| 摘要 |
<p>Process for producing high flow heterophasic propylene copolymers; said process comprises the steps of
- polymerising propylene and optionally an ethylene and/or C 4 -C 12 alpha-olefin comonomer in a slurry reactor in the presence of hydrogen and a polymerisation catalyst system, obtaining as slurry reactor product first propylene polymer fraction (PP1) of the polypropylene matrix
- transferring the slurry reactor product into a 1 st gas phase reactor
- further polymerising propylene and optionally an ethylene and/or C 4 -C 12 alpha-olefin comonomer in the presence of said slurry reactor product, the polymerisation catalyst system and additional hydrogen, obtaining as 1 st gas phase reactor product a mixture of the first propylene polymer fraction (PP1) and a second propylene polymer fraction (PP2), being the polypropylene matrix of the heterophasic propylene copolymer having an MFR 2 in accordance with ISO 1133 (230°C, 2.16 kg) equal to or above 200 g/10min,
- transferring said 1 st gas phase reactor product into a 2 nd gas phase reactor
- producing a first elastomeric propylene copolymer fraction (EPR1), in the presence of said 1 st gas phase reactor product and at least one ethylene and/or C 4 to C 12 ±-olefin, the comonomer/propylene ratio being in the range of 150 to 300 mol/kmol
- transferring the 2 nd gas phase reactor product into a 3 rd gas phase reactor
- producing a second elastomeric propylene copolymer fraction (EPR2) in the presence of said 2 nd gas phase reactor product and at least one ethylene and/or C 4 to C 12 ±-olefin, the comonomer/propylene ratio being in the range of 300 to 1000 mol/kmol and
- recovering the heterophasic propylene copolymer for further processing said polymerisation catalyst system comprising
(i) a Ziegler-Natta procatalyst and
(ii) an organometallic cocatalyst and
(iii) an external donor represented by formula (I)
€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒSi(OCH 2 CH 3 ) 3 (NR 1 R 2 )€ƒ€ƒ€ƒ€ƒ€ƒ(I)
wherein R 1 and R 2 can be the same or different and represent a hydrocarbon group having 1 to 12 carbon atoms.</p> |
