Membrane and process for producing the membrane.

摘要

Membrane in the form of a flat sheet, tube, or hollow fiber having a hydraulic permeability of water of 10 - 100 ml/m<2>/h/mmHg, and having a diffusive permeability to chloride (Cl<->) of more than 10 cm sec x 10<-><4>, preferably more than 12 cm/sec x 10<-><4>, a diffusive permeability to vitamin B12 of more than 2 cm/sec x 10<-><4>, preferably more than 3 cm/sec x 10<-><4>, and a diffusive permeability to inulin of more than 0.5 cm/sec x 10<-><4>, preferably more than 1.0 cm/sec x 10<-><4>.
<??>The membrane is prepared in a process involving the combined use of a high molecular weight swelling agent in the casting solution and partial evaporation of solvent prior to subjecting the membrane to gelling.