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Polyolefin microporous film, method for producing same, separator for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

A non-aqueous electrolyte and microporous membrane technology, which is applied in the field of polyolefin microporous membranes, can solve the problems of improving the pore size and reducing the size of the pores that are difficult to take into account the shutdown characteristics, the safety cannot be obtained, and the pore size becomes larger, so as to suppress dendrites The generation and growth, strength and safety are excellent, and the effect of small pore size

Inactive Publication Date: 2019-12-10
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the pore blocking temperature is as high as 140°C and the time until membrane rupture is as short as 2 minutes (minutes), sufficient safety cannot be obtained.
[0012] In this way, for the microporous membrane obtained by the conventional stretching method, although the control of anisotropy is improved and the shrinkage temperature difference becomes larger, the pore diameter tends to become larger, and it is difficult to achieve both the improvement of the shutdown characteristic and the reduction of the pore diameter.

Method used

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  • Polyolefin microporous film, method for producing same, separator for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery
  • Polyolefin microporous film, method for producing same, separator for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery
  • Polyolefin microporous film, method for producing same, separator for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Examples

Experimental program
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Effect test

Embodiment 1

[0134] PE1 (ultra-high molecular weight polyethylene, weight average molecular weight (Mw): 2.89×10 6 , molecular weight distribution (Mw / Mn): 5.28) 30% by weight and PE2 (high-density polyethylene, weight-average molecular weight: 5.72×10 5, Molecular weight distribution: 4.81) 70% by weight formed polyethylene composition. When the whole polyethylene composition was 100% by weight, the content of the polyethylene component with a molecular weight of 500,000 or less was 59% by weight, and the content of the polyethylene component with a molecular weight of 1,000,000 or more was 26% by weight. Add 71.5% by weight of liquid paraffin to 28.5% by weight of the polyethylene composition, further, based on the mass of polyethylene in the mixture, add 0.5% by mass of 2,6-di-tert-butyl-p-cresol and 0.7% by mass % tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]methane was used as an antioxidant and mixed to prepare a polyethylene resin solution. This polyethylene...

Embodiment 2

[0136] A polyolefin microporous membrane was produced in the same manner as in Example 1 except that the draw ratio in the MD stretching step was 1.4 times. Tables 1 to 3 show the membrane properties of the obtained polyolefin microporous membrane.

Embodiment 3

[0138] A polyolefin microporous membrane was produced in the same manner as in Example 1 except that the draw ratio in the MD stretching step was 1.6 times. Tables 1 to 3 show the membrane properties of the obtained polyolefin microporous membrane.

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Abstract

The present invention provides a polyolefin microporous membrane having a small pore size, excellent shutdown characteristics, and suitable for a separator for a non-aqueous electrolyte secondary battery. The invention provides a polyolefin microporous membrane, which is characterized in that the difference between the shutdown initiation temperature in the MD direction and the maximum shrinkage temperature in the MD direction is above 8.6°C, and the maximum pore diameter is less than 0.036 μm. In addition, the present invention also provides a method for producing a polyolefin microporous membrane, which is characterized in that polyolefin resin containing ultra-high molecular weight polyolefin and a plasticizer are melt-kneaded, formed into a sheet, and the obtained sheet is After stretching in the MD direction and simultaneous biaxial stretching, the stretched sheet is dried.

Description

technical field [0001] The present invention relates to a polyolefin microporous film and a separator for a nonaqueous electrolyte secondary battery using the same, and relates to a polyolefin microporous film excellent in safety and a separator for a nonaqueous electrolyte secondary battery using the same diaphragm. Background technique [0002] For batteries that use non-aqueous electrolytes, such as lithium-ion batteries, a separator that has a shutdown function that shuts down the reaction when the temperature exceeds a predetermined temperature is required to prevent internal short circuits. Generally, battery separators are formed of microporous membranes, and when the temperature rises, they shrink near the melting point, and the microporosity closes, shutting down the battery reaction. In addition, when the temperature continues to rise further, the battery separator changes from contraction to elongation at a certain temperature, and eventually ruptures (melts). ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J9/26H01M2/16H01M10/0566H01M50/406H01M50/417H01M50/491H01M50/494
CPCC08J9/26H01M10/0566H01M2300/0017Y02E60/10H01M50/417H01M50/406H01M50/491H01M50/494B29C48/08B29C48/0018B29B7/88C08J5/2231C08J5/2275H01M50/581H01M50/403H01M10/0525Y02P70/50
Inventor 丰田直树菅田正美石原毅
Owner TORAY IND INC
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