Light weight melt blown webs with improved barrier properties
AssigneeBorealis AG
InventorsJingbo Wang, Markus Gahleitner, Klaus Bernreitner, Joachim Fiebig, Henk Van Paridon, Wilhelmus Sars, Gustaf Tobieson
Life of this patent
Estimating the term…
Abstract
The present invention relates to melt-blown webs having no shots and improved barrier properties, whereby the melt-blown webs are made of a visbroken metallocene-catalyzed propylene homopolymer composition with specified melting temperature Tm, content of 2,1 erythro regiodefects and molecular weight distribution (MWD).
Claims16
A melt-blown web comprising a polypropylene composition comprising:
- (a) 90.000-99.999 wt % of a propylene homopolymer (HPP) polymerized in the presence of a metallocene catalyst, wherein the propylene homopolymer (H—PP) has a content of 2,1 erythro regiodefects as determined from 13C-NMR spectroscopy in the range from 0.50 to 0.80 mol %, and
- (b) 0.001-10.000 wt % of a hydroxylamine ester compound,
- wherein the polypropylene composition in said melt-blown web has
- (i) a melting temperature (Tm) measured by differential scanning calorimetry (DSC) according to ISO 11357 in the range from 152 to 160° C.,
- (ii) a molecular weight Mw(web) (measured with GPC on the web) of between 20000-200000 g/mol, and
- (iii) a molecular weight distribution (MWD) of between 1.5-5.0.
A process for preparing a melt-blown web, comprising the steps of:
- (i) polymerizing a propylene homopolymer (HPP) in the presence of a metallocene catalyst system, wherein the propylene homopolymer (H-PP) has a content of 2,1 erythro regiodefects as determined from 13C-NMR spectroscopy in the range from 0.50 to 0.80 mol %,
- (ii) mixing 90.000 to 99.999 wt % of the propylene homopolymer (HPP) obtained in step (i) together with 0.001-10.000 wt % of a hydroxylamine ester compound,
- (iii) pelletizing the mixture obtained in step (ii) in a pelletizer, and
- (iv) melt-blowing the blend pellets obtained in step (iii) into a web.
A method of improving the melt blown web quality characterized by increased hydrohead determined according to standard test WSP 80.6 (09), the method comprising using a polypropylene composition in a melt-blown web comprising:
- (a) 90.000-99.999 wt % of a propylene homopolymer (HPP) polymerized in the presence of a metallocene catalyst, wherein the propylene homopolymer (H-PP) has a content of 2,1 erythro regiodefects as determined from 13C-NMR spectroscopy in the range from 0.50 to 0.80 mol %, and
- (b) 0.001-10.000 wt % of a hydroxylamine ester compound,
- wherein the polypropylene composition in said melt-blown web has
- (i) a melting temperature (Tm) measured by differential scanning calorimetry (DSC) according to ISO 11357 in the range from 152 to 160° C.,
- (ii) a molecular weight Mw(web) (measured with GPC on the web) of between 20000-200000 g/mol, and
- (iii) a molecular weight distribution (MWD) of between 1.5-5.0.
Dependencies are inferred from the claim text.