PURPOSE: To form a semipermeable membrane having a good hydrophilicity and water resistance by applying a coating layer comprising a uniform mixture of a homogeneously miscible aromatic polyamide and a polyvinylpyrrolidone on a substrate and solidifying the layer.
CONSTITUTION: On a substrate, a uniformly mixed coating of a homogeneously miscible aromatic polyamide and a polyvinylpyrrolidone is established. Subsequently, a semipermeable membrane solidified through drying is formed. A preferable example of a coating liquid-preparing solvent for forming the above- mentioned, uniformly mixed coating is N,N-dimethylacetamide or the like. Preferably, the semipermeable membrane obtained by drying and solidifying is heated in a liquid to improve its retention capacity. The aromatic polyamide for forming films preferably has a Staudinger index of about from 50 to 1,000 cm3/g. Also, the polyvinylpyrrolidone preferably has a molecular weight of from 1,000 to 3,000,000.
UIRI KUROIDAA
KURAUSUUPEETAA KURAIHI
YURUGEN UIRUTOHARUTO
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