COMPOSITE SEMIPERMEABLE MEMBRANE AND PRODUCTION THEREOF

摘要

This invention relates to a composite semipermeable membrane of low-pressure high desalination type having an excellent chlorine resistance and a method for the production thereof. This membrane is composed of a microporous supporting membrane and an ultrathin membrane covering said supporting membrane, wherein the ultrathin membrane comprises a polyamide prepared by the polycondensation of a dicarboxylic acid halide with piperazine and ethylenediamine as the main component and a molar fraction of ethylenediamine polyamide constituents to piperazine polyamide constituents is regulated to be in the range of 0.01 to 0.25, so that the membrane has a high desalination rate, a high fresh water generation rate and a sufficient chlorine durability. Thus it can be used in a small ultrapure water generator and a household water purifier and as a reverse osmosis membrane for treating waste water or the like.