# US 10,246,567 B2 · Polyolefin microporous film

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- Number: US 10,246,567 B2
- Document ID: US10246567B2
- Status: Granted
- Kind: B2
- Application number: 13/142,074
- Filed: 2009-12-25
- Published: 2011-10-27
- Granted: 2019-04-02
- Earliest claimed: 2008-12-26
- Assignees: Asahi Kasei E-Materials Corporation
- Applicants: Takashi Ikemoto; Yoshihiro Imamura
- Inventors: Takashi Ikemoto; Yoshihiro Imamura
- Web page: https://patentgrep.com/patent/US10246567B2

## CPC

- C08J 5/18: Manufacture of films or sheets
- H01M 50/403: Manufacturing processes of separators, membranes or diaphragms
- H01M 50/417: Polyolefins
- H01M 50/489: Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M 50/491: Porosity
- H01M 50/494: Tensile strength
- B29C 55/16: simultaneously
- C08J 2323/02: not modified by chemical after treatment
- H01M 50/406: Moulding; Embossing; Cutting
- 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)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

There is provided a polyolefin microporous film which is excellent in taking-up stability in a production line and a processing line of the polyolefin microporous film, and further in a line for a battery taking-up step, and hardly generates step deviation when a roll thereof has received an impact. The polyolefin microporous film has a compression elastic modulus of 0.1 to 1,000 kPa, and a ratio of a tensile elastic modulus in the longitudinal direction to a tensile elastic modulus in the transverse direction of 1.5 to 7.8.

## Claims

### Claim 1

A biaxially stretched polyolefin microporous film, having a compression elastic modulus of 0.1 to 50 kPa, and a ratio of a tensile elastic modulus in a longitudinal direction to a tensile elastic modulus in a transverse direction of 1.5 to 7.8, wherein
a tensile strength at break in the transverse direction of the biaxially stretched polyolefin microporous film is 50 MPa or more and 500 MPa or less,
an average pore diameter of the polyolefin microporous film is 0.06 to 0.09 μm, and wherein an air permeability of the biaxially stretched polyolefin microporous film is in the range of 10 sec/100 cc to 500 sec/100 cc.

### Claim 2 (depends on 1)

The biaxially stretched polyolefin microporous film according to claim 1, wherein the polyolefin microporous film has a friction coefficient in the transverse direction of 0.2 to 0.7.

### Claim 3 (depends on 1, 2)

The biaxially stretched polyolefin microporous film according to claim 1 or 2, wherein the polyolefin microporous film has a compression elastic modulus of 0.1 to 15 kPa.

### Claim 4 (depends on 1, 2)

The biaxially stretched polyolefin microporous film according to claim 1 or 2, wherein the polyolefin microporous film has been subjected to a hydrophilicizing treatment.

### Claim 5 (depends on 1, 2)

The biaxially stretched polyolefin microporous film roll, obtained by rolling the biaxially stretched polyolefin microporous film according to claim 1 or 2.

### Claim 6 (depends on 1, 2)

A separator for a nonaqueous electrolyte secondary battery, comprising the biaxially stretched polyolefin microporous film according to claim 1 or 2.

### Claim 7 (depends on 6)

A nonaqueous electrolyte secondary battery, comprising the separator for the nonaqueous electrolyte secondary battery according to claim 6, a positive electrode, a negative electrode, and the electrolyte.

### Claim 8 (depends on 1)

The biaxially stretched polyolefin microporous film according to claim 1, wherein an air permeability of the polyolefin microporous film is 80 sec/100 cc or more and 300 sec/100 cc or less.

### Claim 9 (depends on 8)

A separator for a nonaqueous electrolyte secondary battery, comprising the biaxially stretched polyolefin microporous film according to claim 8.

### Claim 10 (depends on 9)

A nonaqueous electrolyte secondary battery, comprising the separator for the nonaqueous electrolyte secondary battery according to claim 9, a positive electrode, a negative electrode, and the electrolyte.

### Claim 11 (depends on 1)

The biaxially stretched polyolefin microporous film according to claim 1 further having the compression elastic modulus of 1 to 15 kPa.