Granted Patent B2

US 12,539,477 · App. 17/779,240 · Granted Feb 3, 2026

Inventors: Jingbo Wang (Linz, AT); Markus Gahleitner (Linz, AT); Klaus Bernreitner (Linz, AT); Joachim Fiebig (Linz, AT); Henk Van Paridon (Averbode, BE); Wilhelmus Sars (Tilburg, BE); Gustaf Tobieson (Stenungsund, SE)

Assignee: BOREALIS AG

B01D39/1623C08F4/65927C08F10/06D01F6/06D04H1/565B01D2239/0622B01D2239/1291D10B2321/022

Abstract

Claims (67)

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 with boron-based cocatalysts.

13 . The filtration medium according to claim 1 , wherein the polypropylene composition is visbroken with any one or more visbreaking agents selected from peroxide, hydroxylamine ester and sulphur compound, or by purely thermal degradation.

14 . The filtration medium according to claim 13 , wherein the polypropylene composition is visbroken with a hydroxylamine ester selected from the group consisting of sterically hindered amine derivatives of the formula:

15 . A process for preparing a filtration medium comprising the steps of:

(i) polymerizing a propylene homopolymer (HPP) in the presence of a metallocene catalyst system,

(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 for visbreaking,

(iii) pelletizing the mixture obtained in step (ii) in a pelletizer, and

(iv) melt-blowing the blend pellets obtained in step (iii) and forming into a filtration medium.

16 . A method of increasing the quality factor of a filtration medium to at least 0.7 when the weight per unit area of the filtration medium is 9.5±1.0 g/m 2 , the method comprising using a polypropylene composition to prepare the filtration medium, 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.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (56)