Patent ID: 7803214

Claim:
An asymmetric hollow-fiber gas separation membrane comprising a polyimide, and having an improved tensile elongation at break of 15% or more as a hollow-fiber membrane itself, the polyimide comprising a repeating unit substantially represented by the following general formula (1): wherein, 20 to 80 mol % of A is a tetravalent unit based on the biphenyl structure represented by the formula (2), 20 to 80 mol % of A is a tetravalent unit based on the diphenylhexafluoropropane represented by the formula (3), 0 to 30 mol % of A is a tetravalent unit based on the phenyl structure represented by the formula (4), 30 to 70 mol % of R is a divalent unit represented by the formula (5) and/or formula (6), wherein, in formula (5), each of R1 and R2 is a hydrogen atom or organic group, and n is any number of 0, 1 and 2, and in formula (6), each of R1 and R2 is a hydrogen atom or organic group, and X is —CH 2 — or —CO—, and 30 to 70 mol % of R is a divalent unit based on the biphenyl structure represented by the formula (7), wherein, in formula (7), Y is a chlorine or bromine atom, and n is any number of 1 to 3.