초록 ▼

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

대표청구항 ▼

[ What is claimed is:] [1.] A microporous membrane comprising a copolyimide, said microporous membrane being formed by a process selected from the group consisting of solution-casting and solution-spinning, wherein said copolyimide comprises the imidization reaction product of the diamine/dianhydrid

[ What is claimed is:] [1.] A microporous membrane comprising a copolyimide, said microporous membrane being formed by a process selected from the group consisting of solution-casting and solution-spinning, wherein said copolyimide comprises the imidization reaction product of the diamine/dianhydride condensation reaction product in a solvent of at least three reactants selected from the group consisting of:(a) two diamines A and A' and(b) two dianhydrides B and B' rein A, A', B, and B' are selected so thatthe homopolymer formed from the reaction of A with B, following heat treatment at .gtoreq.250.degree. C., has a glass-transition temperature of .gtoreq.300.degree. C.,the homopolymer formed from the imidization condensation reaction of A' with B', following heat treatment at .gtoreq.250.degree. C., has a resistance to said solvent that is characterized by absorption of .ltoreq.50 wt % of said solvent in pure form at 20.degree. C. for at least 24 hours, andwherein either said two diamines A and A' or said two dianhydrides B and B', but not both, may be the same, d membrane havinga nitrogen permeance greater than 1 Nm.sup.3 /m.sup.2.hr.atm, anda selectivity for oxygen over nitrogen of less than 2.