Patent ID: 7771518

Claim:
An asymmetric hollow-fiber gas separation membrane made of a soluble aromatic polyimide comprising a repeating unit represented by formula (1), from 10 to 60 mol % of B in formula (1) being a tetravalent unit B1 having a diphenylhexafluoropropane structure represented by formula (2), from 90 to 40 mol % of B in formula (1) being a tetravalent unit B2 having a biphenyl structure represented by formula (3), from 85 to 20 mol % of A in formula (1) being a divalent unit A1 represented by formula (4), wherein R and R′ of formula 4 are each a hydrogen atom or an organic group, and n is 0, 1, or 2, and/or a divalent unit A2 represented by general formula (5), wherein R and R′, each is hydrogen atom or an organic group, and X is —CH 2 — or —CO—; and from 15 to 80 mol % of A in formula (1) being divalent unit A3 represented by general formula (6),