Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Polyolefin Microporous Membrane

Inactive Publication Date: 2008-08-14
ASAHI KASEI CHEM CORP
View PDF11 Cites 31 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0001]The present invention relates to a polyolefin microporous membrane, particularly, to a polyolefin microporous membrane suitable as separators for lithium ion batteries, precision filter membranes, separators for capacitors, and materials for fuel cells.

Problems solved by technology

That is, if the temperature of battery further rises after shut-down of separators, fluidization of separator begins to cause decrease of electrical resistance, resulting in restoration of current.
When electrodes are packed, the inside of the battery is in the state of being densely packed, which causes the problem of low impregnation with electrolyte.
However, according to the technology disclosed in this document, the separators can hardly be thinned, and it is difficult to attain increased capacity of battery per unit volume.
According to this method, since agglomerates passing through the nets are present, the portions where the agglomerates which have passed through the nets are present are low in mechanical strength to cause occurrence of pinholes.
Furthermore, since agglomerates are removed, there sometimes occurs local ununiformity in composition.
Therefore, further thinning of the separator is difficult, and attainment of increase in capacity of battery per unit volume is difficult.
Moreover, only such an organic porous membrane as high in porosity can be produced, and hence the membrane strength tends to decrease.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0088]32 parts by mass of polypropylene (density: 0.90, viscosity average molecular weight: 300,000) and 8 parts by mass of silica (oil absorption: 200 ml / 100 g) as materials of surface layer, 2 parts by mass of bis(p-ethylbenzylidene)sorbitol as a nucleating agent, 0.3 part by mass of tetrakis-[methylene-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane as an antioxidant, and 12 parts by mass of liquid paraffin (kinematic viscosity at 37.78° C.: 75.90 cSt, density: 0.868) as a plasticizer were blended and stirred by a mixer to prepare a raw material. 40 parts by mass of a high density polyethylene (density: 0.95, viscosity average molecular weight: 250,000) as a material of interlayer and 0.3 part by mass of tetrakis-[methylene-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane as an antioxidant were blended to prepare a raw material. The respective blends were introduced through feeders of two twin-screw extruders having a bore diameter of 25 mm and L / D=48. Furthermore, 48 ...

example 2

[0089]A microporous membrane was produced in the same manner as in Example 1, except that a high density polyethylene (density: 0.95, viscosity average molecular weight: 250,000) was used in place of polypropylene as the material of the surface layer. The physical properties of the resulting microporous membrane are shown in Table 1.

example 3

[0090]A microporous membrane was produced in the same manner as in Example 1, except that 36 parts by mass of polypropylene (density: 0.90, viscosity average molecular weight: 300,000) as a material of the surface layer, 4 parts by mass of silica (oil absorption: 200 ml / 100 g) and 6 parts by mass of liquid paraffin as a plasticizer were blended and stirred by a mixer to prepare a raw material, and, furthermore, 54 parts by mass of liquid paraffin was charged in the extruder for the surface layer by side feeding. The physical properties of the resulting microporous membrane are shown in Table 1.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
Lengthaaaaaaaaaa
Lengthaaaaaaaaaa
Percent by massaaaaaaaaaa
Login to View More

Abstract

Disclosed is a polyolefin microporous membrane including a multilayer film having two or more layers. In this polyolefin microporous membrane, at least one surface layer has a thickness of not less than 0.2 μm but not more than 5 μm and contains inorganic particles, while at least one layer contains a polyethylene and has an air permeability of not less than 50 second / 100 cc but not more than 1000 second / 100 cc and a puncture strength of not less than 3.0 N / 20 μm.

Description

TECHNICAL FIELD[0001]The present invention relates to a polyolefin microporous membrane, particularly, to a polyolefin microporous membrane suitable as separators for lithium ion batteries, precision filter membranes, separators for capacitors, and materials for fuel cells.BACKGROUND ART[0002]Polyolefin microporous membranes are used as precision filter membranes, separators for batteries, separators for capacitors, materials for fuel cells, etc., and particularly, used as separators for lithium ion batteries. Recently, lithium ion batteries are used for miniature electronic instruments such as portable telephones and notebook type personal computers, and it is further attempted to apply them to electric cars, small motorbikes, etc.[0003]Polyethylene microporous membranes are used as separators for lithium ion batteries because they are high in permeability, and besides they have a function to clog the communicating pores upon melting the polymer at 130-150° C. and to shut-down the ...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): H01M2/16B32B3/10B32B27/32H01M50/417H01M50/451H01M50/457H01M50/489
CPCB32B27/32H01M2/1686H01M2/1653Y10T428/24998Y10T428/249978Y02E60/10H01M50/417H01M50/457H01M50/451H01M50/489B32B27/08B32B27/18B32B27/205H01M50/411H01M50/449H01M50/491B32B2307/518B32B2457/10B32B2305/026B32B2305/02
Inventor OHASHI, MASAHIROSOGO, HIROSHI
Owner ASAHI KASEI CHEM CORP
Features
  • Generate Ideas
  • Intellectual Property
  • Life Sciences
  • Materials
  • Tech Scout
Why Patsnap Eureka
  • Unparalleled Data Quality
  • Higher Quality Content
  • 60% Fewer Hallucinations
Social media
Patsnap Eureka Blog
Learn More

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2025 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com