PRODUCTION OF MICROPOROUS MEMBRANE

摘要

PURPOSE:To produce a microporous membrane having excellent gas-permeability and gas-separability, by forming a homogeneous membrane from a mixture of a methanol-insoluble polymer and a methanol-soluble three-dimensionally crosslinked silicon copolymer, and immersing the membrane in methanol, etc. to form microscopic pores. CONSTITUTION:A thin film made of a mixture of (A) a methanol-insoluble polymer such as a three-dimensionally crosslinked copolymer of polyhydroxystyrene (or novolak resin)-polysulfone-polydimethyl-siloxane and (B) a methanol-soluble three-dimensionally crosslinked silicone copolymer such as polyhydoxystyrene- polyorganosiloxane copolymer, is formed on a porous substrate to obtain a composite membrane, which is immersed in or contacted with methanol or ethanol to form microscopic pores in the membrane and obtain the objective microporous membrane. The density of the micropores in the homogeneous membrane can be selected arbitrarily by controlling the production condition. The membrane can be used effectively for separating gases having close or much different molecular weights.