| abstract |
Provided is a separation membrane having excellent antifouling properties, hydrophilic properties, and oxidizing agent resistance, as well as excellent desalting performance necessary for application to seawater desalination. A separation membrane comprising a copolymer having a mass average molecular weight of 50,000-1,000,000 and including units represented by formula (1) and units represented by formula (2), in which the salt rejection ate by a cross-flow method is at least 3% at 25°C and 0.45 MPaG using an aqueous solution of sodium chloride having a concentration of 0.15% by mass. In formula (1), X and Y are each independently H, F, CF 3 , or Cl. In formula (2), Z is OR 1 , NHR 2 , COOR 3 , or SO 3 R 4 . In the formulae, R is a bivalent linking group which may include a single bond and an etheric oxygen atom, or a bivalent linking group which may include a ring structure, and R 1 -R 4 are each independently H or a monovalent organic group. Of the units represented by formula (2) included in the copolymer, the ratio of units in which R 1 -R 4 are H is at least 50 mol%. |