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US 11,447,623 B2Granted
Process for preparing a polypropylene composition
AssigneeBorealis AG
InventorsJingbo Wang, Markus Gahleitner, Elisabeth Potter, Jani Aho, Klaus Bernreitner, Luc Monnissen, Meta Cigon
Life of this patent
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Abstract
The invention relates to a process for producing a polypropylene composition by sequential polymerization the polypropylene composition having an improved balanced combination of high flowability, high stiffness and impact, and high level of optical properties.
Claims13
A process for producing a polypropylene composition by sequential polymerization comprising the steps:
- a) polymerizing in a first reactor monomers comprising propylene and optionally one or more comonomers selected from ethylene and C4-C10 alpha-olefins, to obtain a first propylene polymer fraction having a comonomer content in the range of 0.0 to 1.0 wt %;
- b) polymerizing in a second reactor monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins, in the presence of the first propylene polymer fraction, to obtain a second propylene polymer fraction having a comonomer content in the range of 0.3 to 2.0 wt %;
- c) polymerizing in a third reactor monomers comprising propylene and one or more comonomers selected from ethylene and C4-C10 alpha-olefins, wherein the ratio of the one or more comonomers to propylene is in the range of 45.0 to 170.0 mol/kmol, in the presence of the second propylene polymer fraction to obtain a third propylene polymer fraction having a comonomer content in the range of from 1.5 to 5.0 wt %;
- and
- d) extruding the third propylene polymer fraction in the presence of at least one alpha-nucleating agent;
- wherein the polypropylene composition has an MFR2 in the range of from 12.0 to 60.0 g/10 min, as measured according to ISO 1133 at 230° C. under a load of 2.16 kg.
3 more elements
Dependencies are inferred from the claim text.