| 摘要 |
The present invention relates to a process for the preparation of a propylene homo- or copolymer, comprising the following steps:
(i) feeding propylene and hydrogen, and optionally one or more comonomers, to a reactor R1, wherein the hydrogen is fed to the reactor R1 in a periodically varying amount,
(ii) preparing a first fraction of the propylene homo- or copolymer in the reactor R1 in the presence of a catalyst,
(iii) transferring the first fraction to a reactor R2, and
(iv) preparing a second fraction of the propylene homo- or copolymer in the reactor R2,
wherein the melt flow rate MFR(2.16 kg, 230°C) of the propylene homo- or copolymer is higher than the melt flow rate MFR(2.16 kg, 230°C) of the first fraction.
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