Method for making high-temperature-resistance polyolefin microporous membrane

A technology for microporous membranes and manufacturing methods, which can be applied to flat products, applications, household appliances, etc., and can solve the problem of affecting the air permeability and mechanical strength of polyolefin microporous membranes, reducing the shrinkage rate of polyolefin microporous membranes, and blocking the ventilation of diaphragms. Performance and other issues, to achieve the effect of small heat shrinkage, small change in air permeability, and improved high temperature performance

Active Publication Date: 2008-09-17
康辉南通新材料科技有限公司
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Japanese patents JP2004-204162, JP2004-204163, etc. disclose methods of coating stabilizers to improve the high-temperature performance of polyolefin microporous membranes, and the batteries prepared therefrom can achieve a capacity recovery rate of more than 70% after being stored at 85°C for 30 days , but the electrochemical stability of the introduced organic stabilizer has problems during high-current discharge, and there is a hidden danger of clogging the diaphragm after the reaction, resulting in a decrease in air permeability; the method of Japanese patent JP2003-119306 eases the polyolefin by stretching and then shrinking The internal stress in the microporous membrane is to reduce the shrinkage of the polyolefin microporous membrane at high temperature. The shrinkage after stretching needs to be limited to a relatively small range, otherwise it will greatly affect the polyolefin microporous membrane. The air permeability and mechanical strength of the polyolefin microporous membrane, from the point of view of the comprehensive performance of the polyolefin microporous membrane, there are also problems in this improvement method

Method used

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  • Method for making high-temperature-resistance polyolefin microporous membrane

Examples

Experimental program
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Effect test

Embodiment 1

[0023] 27 (% by weight) of high-density polyethylene (weight-average molecular weight 2.7 × 10 5 , melting point 133 ° C), 3 (weight%) UHMWPE (ultra-high molecular weight polyethylene, weight average molecular weight 1.0 × 10 6 , melting point melting point 138 ℃) drop into twin-screw extruder (diameter 78mm, L / D=48, strong mixing type), add 70 (weight %) liquid paraffin (kinematic viscosity) by side feeding port with metering pump 90cst / 40°C), melted and kneaded under the conditions of 200°C and 200 rpm to prepare a polyethylene solution.

[0024] Pass the polyethylene solution through a T-shaped die (die lip opening 1.2 mm, width 260 mm), extrude at a speed of 3 m / min, and cool the cast sheet on a casting roll with a surface temperature of 10 ° C to obtain a 1.0 mm thick Thick slices.

[0025] Stepwise biaxially stretch the thick sheet, and the stretch ratio is vertical × horizontal = 5 × 7 times, wherein the preheating temperature for longitudinal stretching is 115°C, and...

Embodiment 2

[0029] In the heat treatment step, the heat treatment temperature is 130° C., and the treatment time is 5 seconds. Other steps are the same as in Example 1.

Embodiment 3

[0031] In the heat treatment step, the heat treatment temperature is 125° C., and the treatment time is 12 seconds. Other steps are the same as in Example 1.

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Abstract

This invention relates to a manufacturing method for high temperature-proof polyolefin micro-porous films including: a, melting the polyolefin resin and a solvent to a uniform solution, b, extruding said solution out by the mold head of an extrusion machine to be cooled and cast on a roller to become a thick plate, c, stretching the thick plate in dual way to a thin film, d, washing off the solvent on the film, e, stereotyping the film laterally the second time to get the polyolefin porous film characterizing that said film is fixed in two ways vertically and horizontally in short time high temperature process and its high temperature performance is improved greatly.

Description

technical field [0001] The present invention relates to a method for making a polyolefin microporous membrane, in particular to a method for making a polyolefin microporous membrane that can effectively improve the high-temperature performance of a polyolefin microporous membrane, and a lithium-ion battery made of the polyolefin microporous membrane After high-temperature storage, the internal resistance changes little and the capacity recovery rate is high. Background technique [0002] Polyolefin microporous membrane is a film-like material containing micropores. It is widely used in the production of non-aqueous electrolyte battery separators, capacitor separators, various separation membranes, and water treatment membranes. [0003] The production methods of polyolefin microporous membranes include solvent method, stretching and opening method, etc., and solvent method is generally used. The known solvent method is to heat, melt and mix polyolefin and solvent to form a ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B29D7/01B29C71/02B29C55/12B29K23/00
Inventor 罗明俊尤臻刘会权何一帆张伟廖凯明
Owner 康辉南通新材料科技有限公司
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