| 摘要 |
<p>Process for the preparation of a heterophasic propylene copolymer comprising a random propylene copolymer and an elastomeric propylene copolymer, wherein the process is a sequential polymerization process comprising the steps of
(a) polymerizing in a first reactor propylene and ethylene obtaining a first random propylene copolymer fraction,
(b) polymerizing in a second reactor in the presence of the first random propylene copolymer fraction propylene and ethylene, obtaining a second random propylene copolymer fraction, the first random propylene copolymer fraction and the second random propylene copolymer fraction form a random propylene copolymer,
wherein said random propylene copolymer has a comonomer of at least 4.0 wt.-%,
(c) polymerizing in a third reactor in the presence of said random propylene copolymer, propylene and ethylene, obtaining a first fraction of the elastomeric propylene copolymer, said first fraction and said random propylene copolymer form a first intimate mixture,
(d) polymerizing in a fourth reactor in the presence of the first intimate mixture propylene and ethylene, obtaining a second fraction of the elastomeric propylene copolymer, the second fraction and the first intimate mixture form the heterophasic propylene copolymer,
wherein
the heterophasic propylene copolymer has
€¢ a xylene cold soluble content (XCS) in the range of 35 to 55 wt.-%,
and
€¢ a comonomer content in the range of 8.0 to 17.0 wt.-%.</p> |
