Nanometer microporous membrane, and manufacturing method and application thereof

The invention discloses a nano microporous membrane as well as a preparation method and application thereof. The nano microporous membrane is prepared from the following raw materials in parts by mass: 21.3-30 parts of polyolefin, 70-78.5 parts of a processing aid, 0.02-0.1 part of a plasticizer, 0.03 to 0.2 part of an antioxidant and 0.04-0.15 part of a lubricant; wherein the molecular weight ofthe polyolefin ranges from 50,000 to 1,500,000. The polyolefin with a certain molecular weight is mixed with the processing aid according to a certain proportion so that the compounded material meetsthe specific strength requirement; under the action of intermolecular force and additives, the pore diameter of a micropore structure formed by stretching the polyolefin casting base film is greatly reduced and can reach the nanoscale, the 100% protection effect can be achieved, meanwhile, the thickness of the micropore film can be reduced, and the micropore film is more comfortable to wear when being used for mask materia