| 摘要 |
<p>Process for the preparation of a polypropylene in a sequential polymerization process comprising at least two reactors connected in series, wherein said process comprises the steps of (A) producing in a first reactor a first polypropylene fraction,
(B) transferring said first polypropylene fraction in a second reactor,
(C) polymerizing in said second reactor and in the presence of said first polypropylene fraction a second polypropylene fraction obtaining polypropylene composition, wherein
€¢aid first polypropylene fraction has either a melt flow rate MFR 2 (230 °C)of not more than 1.5 g/10min or of more than 2.0 g/10min, and comprises units derived from propylene and optionally at least one C 2 to C 10 ±-olefin different to propylene,
€¢ the polypropylene composition has a melt flow rate MFR 2 (230 °C) of more than 2.0 g/10 min and
€¢ the melt flow rate MFR 2 (230 °C) of the polypropylene composition (PP-C) is different to the melt flow rate MFR 2 (230 °C) of the first polypropylene fraction (PP-1),
€¢ in the first reactor and second reactor (R-2) the polymerization takes place in the presence of a solid catalyst system, said solid catalyst system (SCS) has a porosity of less than 1.40 ml/, comprises a catalyst being the oregano-zirconium compound of formula (I)
wherein
X are legends with a Ã-bond to the zirconium (R),
L 1 are identical residues selected from the group consisting of linear C 1 to C 20 alkyl, branched C 3 to C 20 alkyl, linear C 1 to C 20 alkenyl, branched C 4 to C 20 alkenyl, C 4 to C 12 cycloalkyl, C 1 to C 20 alkyl substituted C 5 to C 20 cycloalkyl, C 6 to C 20 aryl, and C 5 to C 20 cycloalkyl substituted C 1 to C 20 alkyl wherein the cycloalkyl residue is substituted by C 1 to C 20 alkyl,
L 2 are identical residues selected from the group consisting of linear C 1 to C 20 alkyl, branched C 3 to C 20 alkyl, linear C 1 to C 20 alkenyl, branched C 4 to C 20 alkenyl, C 4 to C 12 cycloalkyl, C 1 to C 20 alkyl substituted C 5 to C 20 cycloalkyl, and C 6 to C 20 aryl,
Y is C, Si or Ge, preferably Si,
R 1 is C 1 to C 20 alkyl, C 4 to C 10 cyclo-alkyl, C 6 -C1 2 aryl, C 7 -C 12 arylalkyl, or trimethylsilyl,
R 2 is C 1 to C 20 alkyl, C 4 to C 10 cyclo-alkyl, C 6 -C 12 aryl, C 7 -C 12 arylalkyl, or trimethylsilyl,
and
comprises a cocatalyst (Co) comprising an element (E) of group 13 of the periodic table (IUPAC).</p> |
