Separation membrane

Abstract

The present invention provides a new separation membrane suitable for a membrane separation device (particularly a spiral membrane element). The separation membrane includes: a separation functional layer; a porous support member supporting the separation functional layer; and an intermediate layer disposed between the separation functional layer and the porous support member. The porous support member has a surface facing the intermediate layer. A load area ratio Smr(c1) of the surface determined by a test below is less than 80%. Test: The surface of the porous support member is subjected to a three-dimensional analysis to obtain a load curve prescribed in JIS B0681-2:2018. On the load curve, a height c1 whose difference from a height co at a load area ratio of 0% is equal to a thickness of the intermediate layer is determined. A load area ratio corresponding to the height c1 is read and determined as Smr(c1).

Dependencies are inferred from the claim text.