Propylene random copolymer for use in film applications
AssigneeBorealis AG
InventorsJingbo Wang, Markus Gahleitner, Klaus Bernreitner, Pauli Leskinen, Peter Niedersüss
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Abstract
The present invention is directed to a polypropylene composition (P) comprising a bimodal copolymer of propylene and 1-hexene prepared in the presence of a metallocene catalyst, said bimodal copolymer having a melt flow rate MFR2 in the range of 4.0 to 20.0 g/10 min. Further, the present invention is directed to a method for preparing the copolymer (C) and an article comprising said polypropylene composition (P).
Claims16
A polypropylene composition (P), comprising at least 90.0 wt-%, based on an overall weight of the polypropylene composition (P), of a copolymer (C) of propylene and 1-hexene, having
- i) an overall 1-hexene content in a range of 2.0 to 10.0 wt-%,
- ii) a melt flow rate MFR2 determined according to ISO 1133 (2.16 kg, 230° C.) in a range of 4.0 to 20.0 g/10 min, and
- iii) an amount of 2,1 erythro regio-defects of at least 0.2 mol-%,
- wherein the copolymer (C) has been visbroken with a visbreaking ratio (VR) in a range of 1.5 to 15.0, wherein the visbreaking ratio is determined according to equation (2)
- VR
- =
- MFR
- final
- MFR
- start
- (
- 2
- )
- wherein “MFRfinal” is the melt flow rate MFR2 determined according to ISO 1133 (230° C., 2.16 kg) of the copolymer (C) after visbreaking and “MFRstart” is the melt flow rate MFR2 determined according to ISO 1133 (230° C., 2.16 kg) of the copolymer (C) before visbreaking.
A process for the preparation of a copolymer (C) of propylene and 1-hexene, comprising the steps of
- a) preparing a copolymer (C′) of propylene and 1-hexene having an overall 1-hexene content in a range of 2.0 to 10.0 wt.-% in the presence of a metallocene catalyst (MC),
- b) visbreaking the copolymer (C′) obtained in step a) with a visbreaking ratio (VR) in a range of 1.5 to 15.0, thereby obtaining the copolymer (C),
- wherein the visbreaking ratio is determined according to equation (3)
- VR
- =
- MFR
-
- (
- C
- )
- MFR
-
- (
- C
- ′
- )
- (
- 3
- )
- wherein “MFR(C)” is a melt flow rate 1MFR2 determined according to ISO 1133 (230° C., 2.16 kg) of the copolymer (C) after visbreaking and “MFR(C′)” is melt flow rate MFR2 determined according to ISO 1133 (230° C., 2.16 kg) of the copolymer (C′).
Dependencies are inferred from the claim text.