Polyethylene microporous membrane, process for production thereof, and battery separator

A technology of microporous membranes and manufacturing methods, which can be applied to battery components, electrical components, circuits, etc., and can solve problems such as insufficient compression resistance of microporous membranes, poor compression characteristics of microporous membranes, and poor cycle characteristics. Excellent air permeability and thermal shrinkage characteristics, fast absorption speed, small changes in film thickness and air permeability

Inactive Publication Date: 2008-07-30
TONEN CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the compression resistance of the microporous membranes described in each of the aforementioned patent documents is not sufficient.
If the compression characteristics of the microporous membrane are poor, there is a high possibility that the capacity of the battery will be insufficient (deterioration of the cycle characteristics) when used as a battery separator

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0127] In Mw by 1.5 x 10 6 5% by mass of ultra-high molecular weight polyethylene (UHMWPE, Mw / Mn=8) and Mw is 3.0×10 5 In 100 parts by mass of a polyethylene composition composed of 95% by mass of high-density polyethylene (HDPE, Mw / Mn=8.6), tetrakis[methylene-3-(3,5-ditertene) was dry mixed as an antioxidant 0.375 parts by mass of butyl-4-hydroxyphenyl)-propionate]methane. The Mw measured for the PE composition composed of UHMWPE and HDPE is 3.8×10 5 , Mw / Mn is 10.2, the melting point is 134°C, the crystallization dispersion temperature is 100°C, and the crystallization temperature is 105°C.

[0128] Mw and Mw / Mn of UHMWPE, HDPE, and PE compositions were determined by gel permeation chromatography (GPC) under the following conditions.

[0129] ・Measuring device: GPC-150C manufactured by Waters Corporation

[0130] ・Column: Shodex UT806M manufactured by Showa Denko Co., Ltd.

[0131] ·Column temperature: 135°C

[0132] Solvent (mobile phase): o-dichlorobenzene

[0133] ...

Embodiment 2

[0141] Use 2.0×10 by 5 mass% Mw 6 A polyethylene composition (Mw: 4.0×10 5 , Mw / Mn: 11.0, melting point: 134.5°C, crystallization dispersion temperature: 100°C, crystallization temperature: 105°C), set the first stretching temperature to 117.5°C, and perform the second stretching at a temperature of 130.5°C, A polyethylene microporous membrane was produced in the same manner as in Example 1, except that the temperature in the TD direction was increased by 1.35, and the heat-fixing treatment temperature was set at 130.5°C.

Embodiment 3

[0143] A polyethylene microporous film was produced in the same manner as in Example 1, except that the second stretching temperature and the heat-setting treatment temperature were set to 129° C. using the same polyethylene composition as in Example 2.

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Abstract

PROBLEM TO BE SOLVED: To provide a microporous polyethylene membrane exhibiting little change in thickness and air permeability during compression and having a rapid electrolyte-absorption rate, and to provide its production method and a battery separator formed by such microporous polyethylene membrane.SOLUTION: The microporous polyethylene membrane is made of a polyethylene resin comprising ≤15 mass% of ultra-high molecular weight polyethylene having a mass-average molecular weight of ≥1 x 10<SP POS="POST">6< / SP>. The microporous polyethylene membrane is a single film that has a densely-structured layer comprising an average pore diameter of 0.01-0.05 μm and a coarsely-structured layer having an average pore diameter larger by 1.2-5.0 times than that of the densely-structured layer, both structured layers being adjacent to each other in a thickness direction, wherein a coarsely-structured layer is formed at least on one surface.

Description

technical field [0001] The present invention relates to a polyethylene microporous membrane having a small change in film thickness and air permeability during pressurization and a fast absorption rate of electrolyte, a method for producing the same, and a battery separator. Background technique [0002] Polyolefin microporous membranes are widely used in battery separators mainly for lithium batteries, separators for electrolytic capacitors, moisture-permeable waterproof clothing, and various filter membranes. When a polyolefin microporous membrane is used as a battery separator, its performance greatly affects the characteristics, productivity, and safety of the battery. Therefore, it is required to have excellent air permeability, mechanical properties, thermal shrinkage properties, shut-off properties, ablation properties, and the like. For example, if the mechanical strength is low, the voltage of the battery decreases when used as a battery separator. [0003] As a m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/00C08J9/26H01M2/16
CPCY02E60/10
Inventor 泷田耕太郎菊地慎太郎山田一博中村悌二河野公一
Owner TONEN CHEM CORP
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