COMPOSITE SEMIPERMEABLE MEMBRANE AND METHOD FOR PRODUCING SAME

摘要

Disclosed is a composite semipermeable membrane which is obtained by forming a polyamide separation functional layer on a microporous supporting membrane, said polyamide separation functional layer being obtained by a polycondensation reaction between a polyfunctional aromatic amine and a polyfunctional acid halide. The polyamide separation functional layer has a carboxy group, an amino group, a phenolic hydroxyl group and an azo group. The ratio of the amino group (XA) in the raw water contact surface (surface A) of the polyamide separation functional layer (namely, the molar equivalent of the amino group/(the molar equivalent of the azo group + the molar equivalent of the phenolic hydroxyl group + the molar equivalent of the amino group)) is not more than 0.5, and the ratio of the amino group (XB) in the permeation-side surface (surface B) of the polyamide separation functional layer, said permeation-side surface being on the reverse side of the surface A, (namely, the molar equivalent of the amino group/(the molar equivalent of the azo group + the molar equivalent of the phenolic hydroxyl group + the molar equivalent of the amino group)) is within the range of 0.5-1 (inclusive). The composite semipermeable membrane has a good balance between high solute removing properties and high water permeation rate, while having high organic solvent resistance. Also disclosed is a method for producing the composite semipermeable membrane.