Polymer composition blend and membranes made therefrom

Patent metadata

Field	Value
Publication number	US-12486387-B2
Application number	US-202318124848-A
Country	US
Kind code	B2
Filing date	Mar 22, 2023
Priority date	Mar 22, 2022
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

A polymer composition for producing gel extruded articles is described. The polymer composition contains at least three different polyethylene polymers, namely a lower molecular weight polyethylene polymer, a mid-range molecular weight polyethylene polymer, and a high molecular weight polyethylene polymer. Combining the different polyethylene polymers in different ratios can optimize not only mechanical properties but improve processing.

First claim

What is claimed:

1 . The polymer composition for producing gel extruded articles comprising:
a plasticizer; and polymer particles comprising a first polyethylene polymer, a second polyethylene polymer, and a third polyethylene polymer, the first polyethylene polymer having a molecular weight of from about 300,000 g/mol to about 1 million g/mol, the first polyethylene polymer being present in an amount of from about 3% to about 25% by weight of the polymer particles, the second polyethylene polymer having a molecular weight of from about 1 million g/mol to about 2.9 million g/mol, the second polyethylene polymer being present in an amount of from about 25% to about 85% by weight of the polymer particles, the third polyethylene polymer having a molecular weight of from about 2 million g/mol to about 10 million g/mol, the third polyethylene polymer being present in an amount of from about 5% to about 48% by weight of the polymer particles.

2 . The polymer composition as defined in claim 1 , wherein the polymer particles include polymer particles only made from the first polyethylene polymer, polymer particles only made from the second polyethylene polymer, and polymer particles only made from the third polyethylene polymer.

3 . The polymer composition as defined in claim 1 , wherein the polymer particles include particles that comprise at least two of the polyethylene polymers.

4 . The polymer composition as defined in claim 1 , wherein the first polyethylene polymer has a molecular weight of from about 500,000 g/mol to about 700,000 g/mol, the second polyethylene polymer has a molecular weight of from about 1.5 million g/mol to about 2.1 million g/mol, and the third polyethylene polymer has a molecular weight of from about 4 million g/mol to about 8 million g/mol.

5 . The polymer composition as defined in claim 1 , wherein the first polyethylene polymer is present in an amount of from about 5% to about 15% by weight of the polymer particles, the second polyethylene polymer is present in an amount of from about 50% to about 75% by weight of the polymer particles, and the third polyethylene polymer is present in an amount of from about 20% to about 40% by weight of the polymer particles.

6 . The polymer composition as defined in claim 1 , wherein a membrane formed from the polymer composition has a porosity of from about 35% to about 38% and has a puncture strength greater than 1450 mN/micron and a pin strength of greater than about 252 gf/g/cm 2 .

7 . The polymer composition as defined in claim 1 , wherein a membrane formed from the polymer composition has a porosity of from about 38% to about 50% and has a puncture strength greater than 340 mN/micron and a pin strength of greater than about 72 gf/g/cm 2 .

8 . The polymer composition as defined in claim 1 , wherein the polymer composition has a viscosity number of from about 1000 to about 1800.

9 . The polymer composition as defined in claim 1 , wherein the polymer particles have a median particle size by volume of from about 70 microns to about 210 microns.

10 . The polymer composition as defined in claim 1 , wherein the polymer particles are present in the composition in an amount up to about 50% by weight.

11 . The polymer composition as defined in claim 1 , wherein the plasticizer comprises mineral oil, a paraffinic oil, a hydrocarbon, an alcohol, an ether, an ester, or mixtures thereof.

12 . The polymer composition as defined in claim 1 , wherein the polymer composition is polypropylene-free.

13 . A process for producing polymer articles comprising:
forming the polymer composition as defined in claim 1 into a gel-like composition; extruding the gel-like composition through a die to form a polymer article, the polymer article comprising a film; and removing at least part of the plasticizer from the polymer article.

14 . The porous membrane comprising:
a polymer blend comprising a first polyethylene polymer, a second polyethylene polymer, and a third polyethylene polymer, the first polyethylene polymer having a molecular weight of from about 400,000 g/mol to about 1 million g/mol, the first polyethylene polymer being present in an amount of from about 3% to about 18% by weight, the second polyethylene polymer having a molecular weight of from about 1.1 million g/mol to about 2.9 million g/mol, the second polyethylene polymer being present in an amount of from about 34% to about 85% by weight, the third polyethylene polymer having a molecular weight of from about 3 million g/mol to about 10 million g/mol, the third polyethylene polymer being present in an amount of from about 12% to about 48% by weight, the porous membrane having a tensile strength in a machine direction of greater than about 155 MPa.

15 . The porous membrane as defined in claim 14 , wherein the porous membrane has a porosity of from about 35% to about 38% and has a puncture strength greater than 1450 mN/micron and a pin strength of greater than about 252 gf/g/cm 2 .

16 . The porous membrane as defined in claim 14 , wherein the porous membrane has a porosity of from about 45% to about 50% and has a puncture strength greater than 340 mN/micron and a pin strength of greater than about 72 gf/g/cm 2 .

17 . The porous membrane as defined in claim 14 , wherein the membrane has a thickness of from about 5 microns to about 20 microns and contains a nucleating agent.

18 . The porous membrane as defined in claim 14 , wherein the membrane has a Gurley permeability of greater than about 105 sec/100 ml.

19 . The porous membrane as defined in claim 14 , wherein the porous membrane has been biaxially stretched.

Assignees

• Celanese Int Corp

Inventors

• Tao Fangfang
• Ohm Christian
• Sun Yingying
• Ditter David

Classifications

• H01M50/417

  Polyolefins · CPC title

• C08L2207/068

  Ultra high molecular weight polyethylene · CPC title

• B01D2325/24

  Mechanical properties, e.g. strength · CPC title

• B01D2325/341

  At least two polymers of same structure but different molecular weight · CPC title

• B01D2325/20

  Specific permeability or cut-off range · CPC title