Toyobo Co., Ltd.

Miyuki Yao

Tooru Kitagawa

Seiji Watanuki

Takahito Nakao

Mayumi Akashi

[Problem] To provide a membrane for the forward osmosis method, which keeps a high porosity, reduces concentration polarization by appropriately controlling the pore distribution, achieves both high water permeability and a self-supporting property, and has high chemical durability such that are membrane is applicable to various draw solutions. [Solution] A separation membrane having a structure inclined from an outer surface side to an inner surface side, a ratio between a thickness of a dense layer having a dense polymer density and a thickness of a coarse layer having a coarse polymer density being in a range of 0.25&#x2264;(the thickness of the coarse layer)/[(the thickness of the dense layer)+(the thickness of the coarse layer)]&#x2264;0.6, when measuring polymer density distribution in a thickness direction of the separation membrane by Raman spectroscopy.

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Otsu, Japan

Miyuki Yao