INTEGRALLY ASYMMETRICAL POLYOLEFIN MEMBRANE FOR GAS TRANSFER

摘要

The invention relates to a method for producing hydrophobic polyolefinic membranes for gas transfer via thermally induced liquid-liquid phase separation. A solution of at least one polyolefin in a solvent system having a viscosity lower than 60 mPa s and consisting of a compound A and a compound B is extruded to form a moulded body. Compound A is the solvent and compound B preferably a non-solvent for the polymer and the boiling point of compound A is at least 50 ~C higher than that of compound B. After leaving the nozzle at least one surface of the moulded body is subjected to an atmosphere promoting the evaporation of compound B and then cooled until phase separation and solidification of the polymer-rich phase occur. The integrally asymmetrical membrane produced in this way has a porosity of more than 50 to 75 volume %, a sponge-like, open-cell, microporous support layer without macrovoids and on average isotropic pores, and at least one separating layer with pores not exceeding < 100 nm. The membrane is preferably used for blood oxygenation.