Filtration media made from melt-blown fibers with improved filtration properties

Patent metadata

Field	Value
Publication number	US-12539477-B2
Application number	US-202017779240-A
Country	US
Kind code	B2
Filing date	Dec 3, 2020
Priority date	Dec 4, 2019
Publication date	Feb 3, 2026
Grant date	Feb 3, 2026

Abstract

The present invention relates to filtration media made from melt-blown fibers having improved barrier properties. The melt-blown fibers in the filtration media of the invention are made of a visbroken metallocene-catalyzed propylene homopolymer composition with specified melting temperature Tm and molecular weight distribution (MWD).

First claim

The invention claimed is:

1 . A filtration medium made of melt-blown fibers comprising a polypropylene composition, wherein:
(i) the polypropylene composition comprises a propylene homopolymer (HPP) polymerized in the presence of a metallocene catalyst, (ii) the polypropylene composition has been visbroken, (iii) the polypropylene composition has a melting temperature (T m ) measured by differential scanning calorimetry (DSC) according to ISO 11357 in the range from 152 to 160° C., and (iv) the polypropylene composition has a molecular weight M w (measured with GPC on the filtration medium) of between 20000-200000 g/mol, and a molecular weight distribution (MWD) of between 1.5-5.0.

2 . The filtration medium according to claim 1 , wherein the propylene homopolymer (HPP) has an initial MFR 2 (230° C., 2.16 kg) determined according to ISO 1133 in the range of 20.0-250.0 g/10 min.

3 . The filtration medium according to claim 1 , wherein the propylene homopolymer (HPP) has a xylene cold soluble fraction (XCS) determined at 23° C. according to ISO 16152 in the range from 0.1 wt % to 1.5 wt %.

4 . The filtration medium according to claim 1 , wherein the propylene homopolymer (H-PP) has a content of 2,1 erythro regiodefects as determined from 13 C-NMR spectroscopy in the range from 0.30 to 0.80 mol. %.

5 . The filtration medium according to claim 1 , wherein the final MFR 2 (230° C., 2.16 kg) determined on the filtration medium according to ISO 1133 is in the range of 600.0-5000.0 g/10 min, and/or
the visbreaking ratio [final MFR 2 (230° C./2.16 kg)/initial MFR 2 (230° C./2.16 kg)] is in the range of 5 to 250, wherein the final MFR 2 (230° C./2.16 kg) is the MFR 2 (230° C./2.16 kg) of the polypropylene composition in the filtration medium and the initial MFR 2 (230° C./2.16 kg) is the MFR 2 (230° C./2.16 kg) of the propylene homopolymer (HPP).

6 . The filtration medium according to claim 1 , wherein:
(i) the molecular weight (M w ) ratio of the M w of the filtration medium to the M w of the propylene homopolymer (HPP) [M w (final)/M w (PP)] is <1, and (ii) molecular weight distribution (MWD) ratio of MWD of the filtration medium to MWD of the propylene homopolymer (HPP) [MWD (final)/MWD (PP)] is <1.

7 . The filtration medium according to claim 1 , wherein the polypropylene composition in the filtration medium has a molecular weight distribution (MWD) of between 2.0 to 3.2.

8 . The filtration medium according to claim 1 , wherein the propylene homopolymer (HPP) is polymerised in the presence of a metallocene catalyst complex of formula (I):

wherein
Mt is Hf or Zr;
each X is a sigma-ligand,
each R 1 independently is the same different and is a CH 2 —R 7 group, with R 7 being H or linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, C 6-10 aryl group,
each R 2 is independently a —CH═, —CY═, —CH 2 —, —CHY— or —CY 2 — group, wherein Y is a C 1-10 hydrocarbyl group and where n is 2-6,
each R 3 and R 4 are independently the same or different and are hydrogen, a linear or branched C 1 -C 6 -alkyl group, an OY group or a C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6-20 aryl group, whereby at least one R 3 per phenyl group and at least one R 4 is not hydrogen, and optionally two adjacent R 3 or R 4 groups can be part of a ring including the phenyl carbons to which they are bonded,
R 5 is a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6 -C 20 -aryl group,
R 6 is a C(R 8 ) 3 group, with R 8 being a linear or branched C 1 -C 6 alkyl group,
each R is independently a C 1 -C 20 -hydrocarbyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl or C 7 -C 20 -alkylaryl.

9 . The filtration medium according to claim 8 , wherein the propylene homopolymer (HPP) is polymerised in the presence of a metallocene catalyst complex, wherein
Mt is Zr, each X is independently a hydrogen atom, a halogen atom, C 1-6 alkoxy group or an R′ group, where R′ is a C 1-6 alkyl, phenyl or benzyl group, each R is independently a C 1 -C 20 -hydrocarbyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl or C 7 -C 20 -alkylaryl, each R 1 independently is the same or different and is a CH 2 —R 7 group, with R 7 being H or linear or branched C 1-6 -alkyl group, C 6-10 aryl group, each R 2 is independently a —CH═, —CY—, —CH 2 —, —CHY— or —CY 2 — group, wherein Y is a C 1-4 hydrocarbyl group and where n is 3-4, each R 3 and R 4 are independently the same or different and are hydrogen, a linear or branched C 1 -C 6 -alkyl group or C 6-20 aryl groups, whereby at least one R 3 per phenyl group and at least one R 4 is not hydrogen, R 5 is a linear or branched C 1 -C 6 alkyl group or C 6-20 aryl group and R 6 is a C(R 8 ) 3 group, with R 8 being a linear or branched C 1 -C 4 alkyl group.

10 . The filtration medium according to claim 9 , wherein the propylene homopolymer (HPP) is polymerised in the presence of a metallocene catalyst complex, wherein:
Mt is Zr, each X is independently a chlorine, benzyl or a methyl group, each R is independently a C 1 -C 10 -hydrocarbyl or C 6 -C 10 -aryl group, both R 1 are the same and are a CH 2 —R 7 group, with R 7 being H or linear or branched C 1 -C 3 -alkyl group, each R 2 is independently a —CH═, —CY═, —CH 2 —, —CHY— or —CY 2 — group, wherein Y is a C 1-4 hydrocarbyl group and where n is 3-4, each R 3 and R 4 are independently the same or different and are hydrogen, a linear or branched C 1 -C 6 -alkyl group or C 6-20 aryl groups, whereby at least one R 3 per phenyl group and at least one R 4 is not hydrogen, R 5 is a linear or branched C 1 -C 6 alkyl group or C 6-20 aryl group, and R 6 is a C(R 8 ) 3 group, R 8 being the same and being a C 1 -C 2 -alkyl group.

11 . The filtration medium according to claim 1 , wherein the propylene homopolymer (HPP) is polymerised in the presence of a metallocene catalyst system comprising
(i) a metallocene catalyst complex of formula (I):

wherein
Mt is Hf or Zr;
each X is a sigma-ligand,
each R 1 independently are the same or can be different and are a CH 2 —R 7 group, with R 7 being H or linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, C 6-10 aryl group,
each R 2 is independently a —CH═, —CY═, —CH 2 —, —CHY— or —CY 2 — group, wherein Y is a C 1-10 hydrocarbyl group and where n is 2-6,
each R 3 and R 4 are independently the same or different and are hydrogen, a linear or branched C 1 -C 6 -alkyl group, an OY group or a C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6-20 aryl group, whereby at least one R 3 per phenyl group and at least one R 4 is not hydrogen, and optionally two adjacent R 3 or R 4 groups can be part of a ring including the phenyl carbons to which they are bonded,
R 5 is a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group or C 6 -C 20 -aryl group,
R 6 is a C(R 8 ) 3 group, with R 8 being a linear or branched C 1 -C 6 alkyl group,
each R is independently a C 1 -C 20 -hydrocarbyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl or C 7 -C 20 -alkylaryl; and
(ii) a cocatalyst comprising a compound of a group 13 metal.

12 . The filtration medium according to claim 11 , wherein catalyst system comprises as cocatalyst (ii) alumoxane, combinations of alumoxane with Al-alkyls, boron or borate cocatalysts, and combination of alumoxanes

Assignees

• Borealis Ag

Inventors

• Wang Jingbo
• Gahleitner Markus
• Bernreitner Klaus
• Fiebig Joachim
• Van Paridon Henk
• Sars Wilhelmus
• Tobieson Gustaf

Classifications

• D10B2321/022

  polypropylene · CPC title

• B01D2239/1291

  Other parameters · CPC title

• B01D2239/0622

  Melt-blown · CPC title

• D04H1/565

  by melt-blowing · CPC title

• D01F6/06

  from polypropylene · CPC title