COMPOSITE MEMBRANE AND PRODUCTION THEREOF

摘要

PURPOSE: To obtain a composite membrane having a reduced negative effect of its supporting body to permeability and separation factor of the membrane by specifying an air permeability of a film, the thickness of a coating or the like of the composite membrane including a microporous polymer film as the supporting body and a non-porous gas or vapor separating coating. CONSTITUTION: A composite membrane comprises a microporous polymer film having a high air permeability as a supporting body and a non-porous gas or vapor separating coating thereon. The air permeability of the polymer film measured by Gurley method is <=40 s/50 ml. The actual separation factor of the membrane is at least 80% of the ideal separation factor of the coating and the effective thickness of the coating is not more than 20% greater than the nominal thickness of the layer. In an applying step of coating material to the supporting body, when drawing is started up a first layer is in a liquid state and the viscosity of the first layer is increased during drawing.