Multilayer porous membranes and methods of making the same

Patent metadata

Field	Value
Publication number	US-12496815-B2
Application number	US-202118012915-A
Country	US
Kind code	B2
Filing date	Jul 5, 2021
Priority date	Jul 7, 2020
Publication date	Dec 16, 2025
Grant date	Dec 16, 2025

Abstract

A multilayer membrane comprising at least two co-extruded layers where the two co-extruded layer contain different polymers and one of the two co-extruded layers contains an extrusion additive. Examples of useful extrusion additives may include a nucleating agent or a pore-forming particulate. A method for making the membrane is also disclosed. Using an extrusion additive when co-extruding two different polymers avoids some of the drawbacks associated with processes involving the co-extrusion of different polymers, particularly processes where a co-extruded non-porous precursor is later stretched to form pores. For example, the drawback of lower permeability, difficulty to make lower Gurley, and splittiness may be improved.

First claim

What is claimed is:

1 . An extruded multilayer microporous membrane comprising:
at least one layer that mainly comprises a polymer A, wherein polymer A has a crystallization temperature (T c ); and at least one adjacent layer that mainly comprises a polymer B, which is different than polymer A, and that also comprises an extrusion additive, wherein polymer B has a T c that is different from the T c of polymer A, and wherein polymer B has a T c that is ten degrees or more, twenty degrees or more, thirty degrees or more, or forty degrees or more different than the T c of polymer A; and the one layer and the adjacent layer are co-extruded.

2 . The extruded multilayer microporous membrane of claim 1 , wherein polymer B has a T c that is ten degrees or lower than the T c of polymer A.

3 . The extruded multilayer microporous membrane of claim 1 , wherein polymer A is a polypropylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polypropylene homopolymer, copolymer, or terpolymer.

4 . The extruded multilayer microporous membrane of claim 3 , wherein polymer B is a polyethylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polyethylene homopolymer, copolymer, or terpolymer.

5 . The extruded multilayer microporous membrane of claim 1 , wherein polymer B is a polyethylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polyethylene homopolymer, copolymer, or terpolymer.

6 . The extruded multilayer microporous membrane of claim 1 , wherein the extrusion additive is a nucleating agent that raises or lowers the T c of polymer A by about 5 to about 30 degrees, by about 10 to about 25 degrees, by about 10 to about 20 degrees, by about 10 to 15 degrees, or by about 5 to 10 degrees.

7 . The extruded multilayer microporous membrane of claim 1 , having the following:
the at least one layer that mainly comprises a polymer A; the at least one adjacent layer that comprises mainly a polymer B, which is different than polymer A, and an extrusion additive; and another layer, which is adjacent to the adjacent layer that comprises mainly a polymer B and an extrusion additive, and which itself mainly comprises the polymer A.

8 . The extruded multilayer microporous membrane of claim 1 , wherein the membrane is extruded as part of a cast-film extrusion process or a blown-film extrusion process.

9 . The extruded multilayer microporous membrane film of claim 1 , wherein the membrane is a dry process membrane.

10 . The extruded multilayer microporous membrane of claim 1 , wherein pores of the membrane are at least one of slit-shaped, round, trapezoidal, and irregularly or asymmetrically shaped.

11 . The extruded microporous membrane of claim 1 , comprising a layer structure selected from the following: PP/PE, PP/PE/PP, PP/PE/PE/PP, PP/PE/PE/PE/PP, PP/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PP/PE/PP/PP, PP/PE/PE/PP, PP/PE/PE/PE/PP, PP/PE/PE/PE/PE/PP, PP/PP/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP, or PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP; PP/PP/PP/PE/PP/PP/PP, PP/PP/PP/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, or PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP; PP/PP/PP/PP/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, or PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP wherein
PP is a layer comprising mainly polypropylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polypropylene homopolymer, copolymer, or terpolymer; PE is a layer comprising mainly polyethylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polyethylene homopolymer, copolymer, or terpolymer; at least one PE in each structure comprises an extrusion additive; and wherein the at least one PE with an extrusion additive is coextruded with at least one PP.

12 . The porous membrane of claim 11 , wherein the extrusion additive is a pore-forming particulate having an average particle size from 10 nanometers to 1 micron and being selected from the following: an organic pore-forming particulate, an inorganic pore-forming particulate, and an organic-inorganic pore-forming particulate.

13 . The extruded microporous membrane of claim 1 , comprising a layer structure selected from the following: PP/PE, PP/PE/PP, PP/PE/PE/PP, PP/PE/PE/PE/PP, PP/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP, PP/PP/PE/PP/PP, PP/PE/PE/PP, PP/PE/PE/PE/PP, PP/PE/PE/PE/PE/PP, PP/PP/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP, PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP, or PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP; PP/PP/PP/PE/PP/PP/PP, PP/PP/PP/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP, or PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP; PP/PP/PP/PP/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP, or PP/PP/PP/PP/PE/PE/PE/PE/PE/PE/PE/PE/PE/PE/PP/PP/PP/PP wherein
PP is a layer comprising mainly polypropylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polypropylene homopolymer, copolymer, or terpolymer; PE is a layer comprising mainly polyethylene homopolymer, copolymer, or terpolymer or is a polymer blend containing a polyethylene homopolymer, copolymer, or terpolymer; at least one PP in each structure comprises an extrusion additive; and wherein the at least one PP with an extrusion additive is co-extruded with at least one PE.

14 . The porous membrane of claim 13 , wherein the extrusion additive is a pore-forming particulate having an average particle size from 10 nanometers to 1 micron and being selected from the following: an organic pore-forming particulate, an inorganic pore-forming particulate, and an organic-inorganic pore-forming particulate.

15 . The extruded multilayer microporous membrane of claim 1 , wherein polymer B has a T c that is thirty degrees or more different than the T c of polymer A.

16 . The extruded multilayer microporous membrane of claim 1 , wherein polymer B has a T c that is forty degrees or more different than the T c of polymer A.

17 . The extruded multilayer microporous membrane of claim 1 , wherei

Assignees

• Celgard Llc

Inventors

• Adams Changqing Wang
• Anzini David

Classifications

• B32B2323/10

  Polypropylene · CPC title

• B32B2323/043

  HDPE, i.e. high density polyethylene · CPC title

• B32B2315/00

  Other materials containing non-metallic inorganic compounds not provided for in groups B32B2311/00 - B32B2313/04 · CPC title

• B32B2305/026

  Porous · CPC title

• B32B2264/10

  Inorganic particles · CPC title