COMPOSITE SEMIPERMEABLE MEMBRANE AND METHOD FOR PRODUCING SAME, AND SPIRAL SEPARATION MEMBRANE ELEMENT

摘要

The purpose of the present invention is to provide: a thin composite semipermeable membrane having a practical salt blocking rate and permeation flux; a method for producing said membrane; and a spiral separation membrane element that has a practical salt blocking rate and provides excellent water treatment efficiency. The method for producing the composite semipermeable membrane includes a step in which, while feeding out a porous support body having a porous polymer layer on one surface of a nonwoven fabric layer from a supply roll, an amine solution containing a multifunctional amine component is brought into contact with the porous support body, and an organic solution containing a multifunctional acid halide component is brought into contact with the amine solution on the porous support body to cause interfacial polymerization, thus forming a skin layer containing a polyamide resin on the surface of the porous support body. The method for producing the composite semipermeable membrane is characterized in that the nonwoven fabric layer is 50 to 90 μm thick, and when the moisture content of the porous support body is 100% when being fed out from the supply roll, the amine solution is brought into contact with the porous support body when the rate of decrease of the moisture content of the porous support body is within 15%.