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Microporous membranes and methods for making and using such membranes

A technology of microporous film and polyethylene, applied in transportation and packaging, structural parts, battery pack components, etc., can solve problems such as battery overheating and manufacturing difficulties

Inactive Publication Date: 2013-08-07
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Improved thickness uniformity is desirable as thickness variations cause manufacturing difficulties when the film is wound on a core
Thickness variations can also cause non-isotropic temperature variations in the cell, which can lead to hot spots (areas of higher temperature) in the cell when the separator is thinner

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0082]The method of making the multi-layer microporous membranes of the present invention comprises layering, eg coextrusion, one or more layers comprising a first layer material with one or more layers comprising a second layer material, the first layer comprising The layer of material is on one or both sides of the layer comprising the second layer of material. The first layer material can be prepared by (1) combining a first polyolefin composition and at least one diluent to form a first mixture, (2) extruding the first mixture through a die to form an extrusion (3) cooling the extrudate to form a cooled extrudate, (4) stretching the cooled extrudate in at least one direction to form a stretched sheet, (5) stretching the extrudate from the removing at least a portion of the diluent from the sheet to form a film, (6) stretching the film to form a stretched film, and (7) heat setting the stretched film product of step (6) to form the first micropores layer material. The sec...

Embodiment 1

[0197] (1) Preparation of the first polyolefin solution

[0198] Prepared by dry blending containing (a) 50% with 5.6 x 10 5 Mw and MWD of 4.05 for the first polyethylene resin, (b) 37.5% with 1.1 x 10 6 Mw, heat of fusion of 114 J / g and MWD of 5 for the first polypropylene resin and (c) 12.5% ​​with 6.6 x 10 5 The weight average molecular weight Mw, the heat of fusion of 103.3 J / g and the MWD of 11.4 of the first polyolefin composition of the second polypropylene resin, the percentages are based on the weight of the first polyolefin composition. The polyethylene resin in this composition has a melting point of 135°C and a crystal dispersion temperature of 100°C.

[0199] 25 parts by weight of the obtained first polyolefin composition was charged into a strong blending twin-screw extruder having an inner diameter of 58 mm and an L / D of 42, and 75 parts by mass of liquid paraffin (50 cst, in 40°C) to the twin-screw extruder. Melt blending was performed at 210°C and 200 rpm ...

Embodiment 2

[0206] Example 1 was repeated except that the first and second microporous polyolefin membranes were extruded separately, and then 25 / 50 / 25 in the order of first microporous membrane / second microporous membrane / first microporous membrane Layer thickness than lamination.

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PUM

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Abstract

The present invention relates to a particular multi-layer microporous membrane having a good balance of important properties, including excellent electrochemical stability and low heat shrinkage, while maintaining high permeability and heat resistance, with good mechanical strength, compression resistance and electrolytic solution absorption. The multi-layer microporous membrane of the present invention can be produced by layering, such as for example by coextrusion, one or more microporous membrane second layers and one or more microporous membrane first layers, such as on one or both sides of a second layer. The invention further relates to battery separators comprising the multi-layer microporous membrane and batteries utilizing the battery separators.

Description

technical field [0001] The present invention relates to well-balanced multilayer microporous membranes having important properties when used as battery separators, including excellent electrochemical stability and low thermal shrinkage, as well as high permeability and thermal resistance. This multilayer microporous membrane also has good mechanical strength, electrolytic solution absorption and compression resistance. The present invention also relates to a method for preparing such a multi-layer microporous film, a battery separator comprising such a multi-layer microporous film, and a battery utilizing such a battery separator. Background technique [0002] Microporous polyolefin films can be used as battery separators, for example, in primary and secondary lithium batteries, lithium polymer batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc secondary batteries, etc. battery separator. When microporous polyolefin membranes...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/16H01M10/36H01M10/0525H01M50/406H01M50/417H01M50/491H01M50/494
CPCY02E60/122H01M2/145H01M10/0525Y02T10/7011H01M2/1653Y02E60/10H01M50/417H01M50/406H01M50/491H01M50/494H01M50/489H01M10/0564H01M50/457B29C48/0015B29C48/91C08J5/2231Y02P70/50
Inventor 菊地慎太郎滝田耕太郎
Owner TORAY IND INC