Method for preparing multiple layers of polyolefin microporous film

Abstract

The invention discloses a method for preparing multiple layers of polyolefin microporous film and is used for preparing a polyethylene microporous film by utilizing a wet method. In the method disclosed by the invention, more than two polyolefin resin combinations with low hole closing temperature and high film breaking temperature are adopted; the polyolefin resin with low hole closing temperature and high film breaking temperature and one solvent in long paraffin, mineral oil, vegetable oil and benzoate are mixed into a solution; the polyethylene resin with high film breaking temperature and the solvent which is prepared by blending two or more than two solvents selected from the long paraffin, the mineral oil, the vegetable oil and the benzoate are mixed into a solution; and the polyolefin microporous film is prepared through the steps such as coextrusion, biaxial tension, solvent elution and the like. By the selection of the solvents, the method disclosed by the invention enables the polyolefin resin and the solvents to be easily fused and mixed, has good separation effect and can better control the aperture and thickness of the prepared film. The prepared film has the advantages of low hole closing temperature, high film breaking temperature and high intensity.

Description

technical field [0001] The invention relates to a method for manufacturing a multilayer polyolefin microporous membrane, in particular to a method for manufacturing a multilayer composite polyolefin microporous membrane with low closed cell temperature, high membrane rupture temperature and high strength. Background technique [0002] In 1991, SONY successfully launched the first commercial lithium-ion battery, which has the advantages of high energy density, long life, and high voltage. This secondary battery is widely used in portable electronic products, especially notebook computers and mobile phones. . Lithium-ion batteries usually consist of a lithium oxide positive electrode, a carbon negative electrode, a polymer separator, and an electrolyte. The diaphragm is an important part of the lithium battery. It uses its electrical insulation to separate the positive and negative electrodes of the battery to avoid short circuits. At the same time, its special structure allo...

AI Technical Summary

Problems solved by technology

[0004] In recent years, with the increasing shortage of traditional energy sources in the world, more and more devices have begun to use lithium batteries. Especially in recent years, the development of electric vehicles has put forward higher requirements for the performance of lithium batteries, while traditional single-layer polymerization Material separators such as polyethylene separators and polypropylene separators are difficult to meet the new requirements due to the difficulty of having both low closed cell temperature and high membrane rupture temperature.