Composite microporous membrane containing nanofiber-shaped porous layer oriented in transverse stretching direction

A transverse stretching and nanofiber technology, applied in the field of microporous membranes, can solve the problems of increasing production costs, affecting ion transport performance, and reducing the yield of microporous membranes.

Active Publication Date: 2019-10-18
BEIJING NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When coating the surface of the single-layer polyethylene porous membrane that has been prepared, the yield of the microporous membrane will decrease, which will increase the production cost
At the same time, if the coating is coated on the surface of the microporous membrane, if the porosity of the coating is low, the gas permeability will be reduced. When used as a lithium-ion battery separator, it will affect the ion transmission performance, thereby affecting the battery performance.

Method used

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  • Composite microporous membrane containing nanofiber-shaped porous layer oriented in transverse stretching direction
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  • Composite microporous membrane containing nanofiber-shaped porous layer oriented in transverse stretching direction

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preparation example Construction

[0048] [Preparation of composite microporous membrane]

[0049] [the first method]

[0050] In a solution of the present invention, the composite microporous membrane can be prepared by the following method:

[0051] Coating a coating solution on one side or both sides of the longitudinally stretched film, and then stretching in the transverse direction, the composite microporous membrane is prepared. The composite microporous membrane includes at least one layer of polypropylene porous base layer and the At least one layer of non-polyolefin polymer porous layer in the form of nanofibers oriented along the transverse stretching direction of the composite microporous membrane on one or both sides of the polypropylene porous base layer.

[0052] In one solution of the present invention, the longitudinally stretched film is coated and then subjected to a transverse stretching process, wherein the longitudinally stretched film is subjected to transverse stretching to prepare the ...

Embodiment 1

[0145] The homopolypropylene resin whose melt index is 2.5g / 10min is mixed with the polypropylene beta crystal nucleating agent N,N-dicyclohexyl-2,6 naphthalene diamide accounting for 0.03wt% of the homopolypropylene resin, and mixed uniformly in After melting at a temperature of 200-250°C, a polypropylene layer melt is formed;

[0146] After the polypropylene layer melt is extruded through a T-die, it is cooled and crystallized on a casting roll at 128°C to obtain a polypropylene film containing β crystals, that is, a high β crystal film. After stretching the film 4.5 times longitudinally at 100°C, the two surfaces are respectively coated with an aqueous dispersion with a solid content of 20% and a polyvinylidene fluoride particle size of 200nm to form a coating with a thickness of 6 microns, and then enter In the transverse stretching system, 3.0 times transverse stretching is carried out at 135° C. to obtain a composite polypropylene microporous membrane with a thickness of...

Embodiment 2

[0149] After the homopolypropylene resin with a melt index of 2.5g / 10min is melted at a temperature of 200-250°C by a single-screw extruder, it is extruded through a T-shaped die and wound at a speed of 50m / min to obtain a highly oriented Polypropylene diaphragm. After the polypropylene film is annealed and crystallized at 125°C, a polypropylene pre-stretched film is obtained. After the polypropylene pre-stretched film is pre-stretched by 40% at 30°C, it is further stretched by 50% at 125°C to obtain a longitudinally stretched film with a porosity of 30%. The two surfaces of the longitudinally stretched film are respectively coated with an aqueous dispersion with a solid content of 20% and a polyvinylidene fluoride particle size of 200nm to form a coating with a thickness of 6 microns, and then enter the transverse stretching system at 140°C. 4.0 times transverse stretching to obtain a composite polypropylene microporous membrane with a thickness of 20 microns. The thickness...

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Abstract

The invention provides the composite microporous membrane containing a -shaped porous layer oriented in a transverse stretching direction, wherein the composite microporous membrane comprises at leastone porous base layer and at least one layer of nano-fibrous non-polyolefin polymer porous layer which is positioned on one side or two side surfaces of the porous base layer and is oriented along the transverse stretching direction of the composite microporous membrane; the nano-fibrous non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite microporous membrane can suppress the longitudinal cracking of the composite microporous membrane in the using process, so that the usability of the composite microporous membrane is improved. The compositemicroporous membrane is used in a lithium ion battery, so that the infiltration performance of an electrolyte on the membrane can be effectively improved, the cycling and using performances of the battery can be improved, and the service life of the lithium ion battery can be prolonged.

Description

[0001] This application requires the prior application of the patent application number 201810302163.3 submitted to the State Intellectual Property Office of China on April 4, 2018, and the title of the invention is "a composite porous membrane containing a nanofibrous porous layer oriented along the transverse stretching direction" priority. The entirety of the prior application is incorporated by reference into the present application. technical field [0002] The invention belongs to the technical field of microporous membranes, and in particular relates to a composite microporous membrane containing nanofibrous porous layers oriented along a transverse stretching direction. Background technique [0003] Polyolefin microporous membrane is a kind of polymer membrane, which is a porous membrane with a pore size between 5nm and 1000nm. It is widely used in breathable materials (such as diapers, medical dressings, clothing linings, etc.), liquid separation Materials, ultrafi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36
CPCH01M4/362Y02E60/10
Inventor 周建军胡志宇李林
Owner BEIJING NORMAL UNIVERSITY
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