Toray Industries, Inc.

Tomoko Mitsuhata

Takao Sasaki

Kentaro Takagi

Yutaro Suzuki

Katsufumi Oto

Takashi Yoshino

Kiyohiko Takaya

Takeharu Inoue

Provided is a semipermeable membrane having at least a separating functional layer, wherein azo compounds are retained in the separating functional layer, and the separating functional layer has a yellow index of 10 to 40. Also provided is a method of producing the semipermeable membrane. The present invention provides a semipermeable membrane having not only high water permeability but also high rejection performance even for substances that are nondissociative in the neutral range, such as boric acid, and showing high durability and a manufacturing method therefor.

Semipermeable membrane and manufacturing method therefor

A composite semipermeable membrane comprising a porous support membrane on which a separating functional polyamide layer resulting from the polycondensation reaction of polyfunctional aromatic amines with polyfunctional acid halides is formed, wherein the separating functional polyamide layer has carboxy groups, amino groups, phenolic hydroxyl groups, and azo groups, wherein X, the ratio of the amino groups (molar equivalent of the amino groups/(molar equivalent of the azo groups+molar equivalent of the phenolic hydroxyl groups+molar equivalent of the amino groups)) on a feed water contact surface of the separating functional polyamide layer (an A surface), is in the range 0.5 or less, and X, the ratio of the amino groups (molar equivalent of the amino groups/(molar equivalent of the azo groups+molar equivalent of the phenolic hydroxyl groups+molar equivalent of the amino groups)) on a permeate-side surface of the separating functional polyamide layer (a B surface), i.e., the opposite side to the A surface, is in the range of 0.5 to 1. The present invention provides a composite semipermeable membrane that achieves a balance between high solute removal properties and a high permeate flow rate and has high organic-solvent resistance, and a method for producing same.

Composite semipermeable membrane and method for producing same

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Otsu, Japan

Tomoko Mitsuhata