Microporous film and process for the production thereof

摘要

Microporous film of ultra high molecular weight polyethylene with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range and a process for the production of a film with a high degree of moisture vapor transmission rate and a permeability to air that lies within a narrow range from a polyolefin by extruding a solution of the polyolefine in a first solvent, followed by cooling, the removal of the solvent and stretching of the film, in which the surface of one and only one side of the film is brought into close contact with a second solvent for the polyolefin before the film is contacted with the cooling agent.