| 摘要 |
<p>A membrane in the form of a flat or tubular film or a hollow fibre of polycarbonate/polyether block copolymer with polyethylene oxide blocks having a molecular weight of 1000 to 20,000, the intrinsic viscosity being 180-300 ml/g, measured in chloroform at 25.degree.C., the membrane has an ultrafiltration rate of 4 to 200 ml/h.m2.mm Hg; the copolymer contains 5 to 35%, by weight, of recurring alkylene ether carbonate units and 95 to 65%, by weight, of recurring bisphenol A carbonate units; the membrane can be employed for haemofiltration of dialysis patients suffering from high blood pressure, and can be stored and handled in a dry state; the membrane can be produced in a technologically simplified process in which the block copolymer is homogeneously mixed with .gamma.-butyrolactone at a temperature of 80 to 120.degree.C in a first dissolving stage, the mixture is then converted into a true solution at 140 to 180.degree.C in less than 10 minutes in a second dissolving staye and, after filtration, the solution is cooled to 20 to 50.degree.C, and this solution is extruded through a die into a bath containing a non-solvent for the polymer to give a tubular film, flat film or hollow filament and this extruded material is washed with the aid of washing baths and treatment baths until free from solvent, to the limit of detection, and is dried under conditions which prevent shrinkage in the longitudinal and transverse dimensions.</p> |
