Mfg. acrylonitrile! membrane e.g. for water desalting - by dissolving polyacrylonitrile in DMF, shaping into membrane, removing solvent using different solns. on both sides and stretching

摘要

Process comprises (i) dissolving acrylonitrile polymer in DMF soln. contg. formamide; (ii) shaping to a desirable form of membrane by keeping the soln. at above gelation temp.; (iii) removing solvent from the membrane by contacting one surface of the membrane with aq. soln. 15 degrees C contg. >=20 wt. % of water soluble solvent which have compatibility with above mixture solvent, and then removing solvent from the membrane by contacting other surface of the membrane with aq. soln. 0 degree C contg. 50 wt. % of water soluble solvent which have compatibility with the mixed solvent; and (iv) elongating the resulting solidified membrane. Since both surfaces of the membrane are treated by different processes, the resulting membrane exhibits an excellent water permeability, the removing capacity of salt and mechanical strength.