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US 10,870,937 B2Granted
Melt-blown webs without shots and with improved barrier properties
AssigneeBorealis AG
InventorsJoachim Fiebig, Henk Van Paridon, Jingbo Wang, Markus Gahleitner, Wilhelmus Henricus Adolf Sars, Antti Tynys
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Abstract
Melt-blown webs having no shots and improved barrier properties, whereby the melt-blown webs are made out of a so-called “controlled rheology” propylene (CR-PP), which was visbroken without any peroxide.
Claims11
A method of preparing a melt-blown web which is free of shots, the method comprising blowing a molten polypropylene composition from an extruder die tip onto a conveyer or take-up screen, wherein the polypropylene composition comprises
- (A) a propylene polymer and
- (B) optionally a polymeric nucleating agent,
- wherein the polypropylene composition has
- (i) a melt flow rate MFR2 (230° C./2.16 kg) measured according to ISO 1133 of 20 to 5000 g/10min and
- (ii) a melting temperature Tm between ≥130° C. and ≤170° C. and
- (iii) a molecular weight distribution (MWD)>2
- (iv) wherein the propylene polymer has been polymerized in the presence of a) a Ziegler-Natta catalyst (ZN-C) comprising compounds (TC) of a transition metal of Group 4 to 6 of IUPAC, a Group 2 metal compound (MC) and an internal donor (ID), b) optionally a co-catalyst (Co), and c) optionally an external donor (ED), and
- (v) wherein the polypropylene composition has been visbroken without the use of peroxides.
5 more elements
Dependencies are inferred from the claim text.