# US 12,110,382 B2 · Polyolefin microporous membrane

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- Number: US 12,110,382 B2
- Document ID: US12110382B2
- Status: Granted
- Kind: B2
- Application number: 16/753,121
- Filed: 2019-08-09
- Published: 2021-07-15
- Granted: 2024-10-08
- Earliest claimed: 2019-03-04
- Assignees: Asahi Kasei Kabushiki Kaisha
- Applicants: Asahi Kasei Kabushiki Kaisha
- Inventors: Akihisa Yamashita; Manabu Sekiguchi
- Web page: https://patentgrep.com/patent/US12110382B2

## CPC

- C08J 5/18: Manufacture of films or sheets
- C08L 23/06: Polyethylene
- C08J 9/26: by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
- H01M 50/409: Separators, membranes or diaphragms characterised by the material
- H01M 50/417: Polyolefins
- H01M 50/491: Porosity
- C08J 9/28: by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
- C08J 2323/06: Polyethene
- C08J 2423/12: Polypropene
- H01M 50/494: Tensile strength
- Y02E 60/10: Energy storage using batteries
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided is a polyolefin microporous membrane having a loss tangent (tan δ) at 230° C. of 0.35 or more and less than 0.60 in melt viscoelasticity measurement.

## Claims

### Claim 1

A polyolefin microporous membrane having a loss tangent (tan δ) at 230° C. of 0.35 or more and less than 0.60 in melt viscoelasticity measurement.

### Claim 2 (depends on 1)

The polyolefin microporous membrane according to claim 1, having maximum loads in MD and TD both of 3.0 gf or less in TMA measurement.

### Claim 3 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a storage modulus (G′) at 230° C. of 5.0×104 Pa or more in melt viscoelasticity measurement.

### Claim 4 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a difference between a loss tangent at 190° C. (tan δ190) and a loss tangent at 230° C. (tan δ230) (tan δ230−tan δ190) of −0.05 or less (the difference≤−0.05) in melt viscoelasticity measurement.

### Claim 5 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a difference between a storage modulus at 190° C. (G′190) and a storage modulus at 230° C. (G′230) (G′230−G′190) of −1.0×103 Pa or more (the difference ≥−1.0×103 Pa) in melt viscoelasticity measurement.

### Claim 6 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a difference between a storage modulus at 230° C. (G′230) and a storage modulus at 280° C. (G′230) (G′280−G′230) of −2.1×104 Pa or more (the difference ≥−2.1×104 Pa) in melt viscoelasticity measurement.

### Claim 7 (depends on 1)

The polyolefin microporous membrane according to claim 1, having loads at 160° C. in MD and TD both of 0.10 gf/10 μm or more in TMA measurement.

### Claim 8 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a shutdown temperature of 150° C. or lower when measured at an increasing temperature rate of 15° C./min.

### Claim 9 (depends on 1)

The polyolefin microporous membrane according to claim 1, having an average pores size determined by a half dry method of 0.05 μm or more and 0.08 μm or less.

### Claim 10 (depends on 1)

The polyolefin microporous membrane according to claim 1, having a difference between a maximum pore size determined by a bubble point method and an average pore size determined by a half dry method of 0.01 μm or more and 0.02 μm or less.

### Claim 11 (depends on 1)

The polyolefin microporous membrane according to claim 1, formed from a polyolefin resin composition in which a polyolefin resin occupies 50% by weight or more and 100% by weight or less of resin components constituting the membrane.

### Claim 12 (depends on 1)

The polyolefin microporous membrane according to claim 1, wherein resin components constituting the membrane comprise polyethylene and polypropylene, and a proportion of the polypropylene is 1% by weight or more and 10% by weight or less based on a total amount of polyolefin resins in the resin components as 100% by weight.

### Claim 13 (depends on 1)

A separator for a battery comprising the polyolefin microporous membrane according to claim 1.