Membrana Gmbh

Thomas Batzilla

Friedbert Wechs

Frank Wiese

Erich Kessler

Process for producing an integrally asymmetrical hydrophobic polyolefinic membrane with a sponge-like, open-pored, microporous support structure and a separation layer with a denser structure, using a thermally induced liquid-liquid phase separation process. A solution of at least one polyolefin is extruded to form a shaped object. The solvent used is one for which the demixing temperature of a solution of 25% by weight of the polyolefin in this solvent is 10 to 70&#xb0; C. above the solidification temperature. After leaving the die, the shaped object is cooled using a liquid cooling medium that does not dissolve the polymer up to the die temperature, until the phase separation and solidification of the high-polymer-content phase take place. The integrally asymmetrical membrane producible in this manner has a porosity of greater than 30% to 75% by volume, a sponge-like, open-pored, microporous support layer without macrovoids and with on average isotropic pores, and on at least one of its surfaces a separation layer with pores &#x3c;100 nm, if any. The membrane is preferably used for gas separation or gas transfer processes, in particular for oxygenation of blood.

Process for producing polyolefin membrane with integrally asymmetrical structure

Process for producing integrally asymmetrical hydrophobic polyolefinic membranes with a separation layer, in particular for gas exchange, via thermally induced liquid-liquid phase separation. A solution of at least one polyolefin in a solvent system containing a compound A and a compound B is extruded to form a shaped object. Compound A is a strong solvent and compound B a weak non-solvent for the polymer. After leaving the die, the shaped object is cooled using a solid or liquid cooling medium, which does not dissolve the polymer and does not react chemically with it, until the phase separation and solidification of the high-polymer-content phase take place. The integrally asymmetrical membrane producible in this manner has a porosity of greater than 30% to 75% by volume, a sponge-like, open-pored, microporous support layer without macrovoids and on average isotropic pores, a separation layer on at least one of its surfaces with pores <100 nm, if any, and a gas separation factor &agr;(CO /N ) of at least 1. The membrane is preferably used for blood oxygenation.

Integrally asymmetrical polyolefin membrane

Process for producing an integrally asymmetrical hydrophobic polyolefinic membrane with a sponge-like, open-pored, microporous support structure and a separation layer with a denser structure compared to the support structure, via a thermally induced liquid-liquid phase separation process. A solution of at least one polyolefin in a solvent system consisting of a compound A and a compound B is extruded to form a shaped object. Compound A is a weak solvent and compound B a non-solvent for the polymer. After leaving the die, the shaped object is cooled using a solid or liquid cooling medium that does not dissolve or react chemically with the polymer at temperatures up to the die temperature, until the phase separation and solidification of the high-polymer-content phase take place.

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Bürgstadt, Germany

Thomas Batzilla