Borealis Ag

Meta Cigon

Jingbo Wang

Elisabeth Potter

Luc Monnissen

Markus Gahleitner

Klaus Bernreitner

Susanne Margarete Kahlen

Hermann Braun

Daniela Mileva

Susanne Kahlen

Yi Liu

Jani Aho

Philip Knapen

A heterophasic polypropylene composition comprises a matrix based on a propylene-random copolymer and a linear low density polyethylene dispersed in the matrix. The heterophasic polypropylene composition has both improved impact strength and reduced amount of fraction soluble in cold xylene (XCS), while maintaining optical properties. Further, the heterophasic polypropylene composition has an optimised ratio of impact strength to the amount of fraction soluble in cold xylene (XCS).p.

Heterophasic polypropylene composition

A process for producing a cap or closure comprising obtaining a polypropylene composition by sequential polymerization comprising the steps: A) polymerizing in a first reactor, preferably a slurry reactor, in the presence of a Ziegler-Natta catalyst 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 1.8 wt %, and a MFR2 in the range of from 12.0 to 40.0 g/10 min, as measured according to ISO 1133 at 230° C. under a load of 2.16 kg; B) polymerizing in a second reactor, preferably a first gas-phase 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, wherein the polypropylene composition comprising said first and second propylene polymer fractions 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, has a comonomer content in the range of from 2.2 to 5.0 wt % and wherein the ratio of the comonomer content of component A) to the comonomer content of the polypropylene composition is 0.35 or less, C) melting, extruding and moulding the polypropylene composition in the presence of at least one nucleating agent to prepare a cap or closure; and D) exposing the cap or closure obtained in step (C) to a cooling rate of 50 K/s or more.

Process for preparing a cap or closure

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.

Process for preparing a polypropylene composition

The invention relates to a process for producing a polypropylene composition having an improved balanced combination of high flowability, high stiffness and impact, and high level of optical properties. Further, the invention relates to the polypropylene composition having the above-mentioned properties, as well as an article comprising the polypropylene composition.

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Vienna, Austria

Meta Cigon