US 12,202,180 B2
Process for preparing a cap or closure
Jingbo Wang, Linz (AT); Markus Gahleitner, Linz (AT); Elisabeth Potter, Linz (AT); Luc Monnissen, Arsimont (BE); Meta Cigon, Vienna (AT); and Daniela Mileva, Linz (AT)
Assigned to Borealis AG, Vienna (AT)
Appl. No. 17/607,059
Filed by BOREALIS AG, Vienna (AT)
PCT Filed Apr. 28, 2020, PCT No. PCT/EP2020/061795
§ 371(c)(1), (2) Date Oct. 28, 2021,
PCT Pub. No. WO2020/221765, PCT Pub. Date Nov. 5, 2020.
Claims priority of application No. 19171610 (EP), filed on Apr. 29, 2019.
Prior Publication US 2022/0227030 A1, Jul. 21, 2022
Int. Cl. B29C 45/72 (2006.01); B29C 45/00 (2006.01); B29C 48/00 (2019.01); C08F 110/06 (2006.01); B29C 45/46 (2006.01); B29K 23/00 (2006.01); B29L 31/56 (2006.01)
CPC B29C 45/0001 (2013.01) [B29C 45/7207 (2013.01); B29C 48/00 (2019.02); C08F 110/06 (2013.01); B29C 45/46 (2013.01); B29K 2023/12 (2013.01); B29L 2031/56 (2013.01)] 21 Claims
OG exemplary drawing
 
1. 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, 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;
B1) 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,
wherein the polypropylene composition comprising said first and second propylene polymer fractions and optionally a third propylene polymer fraction 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 the first propylene polymer fraction 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 50K/s or more.