Microporous polyolefin membrane, separator for battery, and production processes therefor

A technology of a microporous membrane and a manufacturing method, which can be used in the manufacture of hybrid/electric double layer capacitors, battery pack components, hybrid capacitor separators, etc., and can solve problems such as membrane rupture

Active Publication Date: 2018-12-21
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, if the internal temperature of the battery continues to rise after the pores are closed for some reason, membrane rupture may occur due to shrinkage of the polyethylene microporous membrane

Method used

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  • Microporous polyolefin membrane, separator for battery, and production processes therefor
  • Microporous polyolefin membrane, separator for battery, and production processes therefor
  • Microporous polyolefin membrane, separator for battery, and production processes therefor

Examples

Experimental program
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preparation example Construction

[0082] (a) Preparation process of polyolefin resin solution

[0083] As a step of preparing a polyolefin resin solution, a molding solvent is added to a polyolefin resin, followed by melt-kneading to prepare a polyolefin resin solution. As the melt-kneading method, for example, the method using a twin-screw extruder described in JP-A-06-104736 and JP-A-3347835 can be utilized. The melt-kneading method is known, and thus description thereof is omitted.

[0084] The molding solvent is not particularly limited as long as it can sufficiently dissolve polyolefin. For example, aliphatic hydrocarbons or cyclic hydrocarbons such as nonane, decane, undecane, dodecane, and liquid paraffin, or mineral oil fractions with corresponding boiling points, etc., but non-volatile hydrocarbons such as liquid paraffin are preferred. solvent.

[0085]The polyolefin resin concentration in the polyolefin resin solution is preferably 25 to 40 parts by weight based on 100 parts by weight of the tota...

Embodiment

[0147] Hereinafter, although an Example is shown and it demonstrates concretely, this invention is not limited to these Examples at all. In addition, the measured value in an Example is the value measured by the following method.

[0148] 1. Determination of the variation range of F25 value

[0149] The polyolefin microporous membranes obtained in Examples and Comparative Examples are at equal intervals in the width direction from positions at a distance of 100 m or more from both ends in the longitudinal direction and at positions 30 mm to 40 mm from the ends in the width direction. Test pieces (TD10mm×MD50mm) were cut out from four positions. According to JIS K7113, using a desktop precision universal testing machine (automatic plotter AGS-J (manufactured by Shimadzu Corporation)), the SS curve (vertical stress and vertical strain) in the longitudinal direction of the test piece was obtained. )Relationship). The vertical stress value at the time of vertical strain elongat...

reference example 1

[0182] Mix polyvinyl alcohol (average degree of polymerization is 1700, degree of saponification is over 99%), alumina particles (average particle size is 0.5 μm), and ion-exchanged water in a weight ratio of 6:54:40 and stir well, to spread evenly. This was filtered using a filter with a filtration limit of 5 μm to obtain a coating liquid (a).

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Abstract

The present invention provides a microporous polyolefin membrane which has a thickness of 3 Mum or larger but less than 7 Mum and which is suitable for forming thereon a porous layer in an even thickness; and a separator for batteries which comprises the microporous polyolefin membrane and a porous layer formed thereon in an even thickness and which is suitable for heightening the capacities of batteries. The microporous polyolefin membrane has a width of variations in longitudinal-direction F25 value of 1 MPa or less and has a thickness of 3 Mum or larger but less than 7 Mum and a length of 1,000 m or longer. (The term "F25 value" indicates a value obtained by dividing the load at 25% specimen elongation measured with a tensile tester by the cross-sectional area of the specimen.)

Description

technical field [0001] The present invention relates to a polyolefin microporous membrane, a battery separator having a porous layer on at least one surface of the polyolefin microporous membrane, and methods for producing the same. Background technique [0002] Microporous membranes made of thermoplastic resins are widely used as material separation membranes, permselective membranes, separators, and the like. For example, battery separators used in lithium-ion secondary batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and polymer batteries; separators for electric double-layer capacitors; various filters such as reverse osmosis filtration membranes, ultrafiltration membranes, and microfiltration membranes ; Waterproof and moisture-permeable fabrics; medical materials; and so on. [0003] In particular, as a separator for lithium-ion secondary batteries, a microporous membrane made of polyethylene is suitably used, which has ion permeability by being im...

Claims

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Application Information

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IPC IPC(8): C08J9/28B29C55/14H01G11/52H01M2/16B29L7/00B29L9/00C08J7/043H01M50/403H01M50/406H01M50/414H01M50/417H01M50/42H01M50/426H01M50/443H01M50/451H01M50/457H01M50/489H01M50/491
CPCH01G11/52B29L2031/3468B29D7/01B29C55/143B29K2105/041B29L2007/002C08J2323/06H01G11/84C08J5/18C08J2429/04C08J2427/16C08J7/0427Y02E60/10H01M50/403C08J7/043H01M50/417H01M50/457H01M50/491H01M50/443H01M50/42H01M50/406H01M50/451H01M50/414H01M50/489H01M50/426B29C55/14C08J9/28C08J9/365Y02E60/13C08J5/2231H01M50/409H01M50/411H01M50/449
Inventor 水野直树菅田正美
Owner TORAY IND INC
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