3m Innovative Properties Company

Ina Voigt

Wolfgang Ansorge

Michael Schmidt

Florentin Michael Wilfart

Jan Haelssig

Hydrophobic poly(4-methyl-1-pentene) hollow fiber membrane for retention of anesthetic agents with an inner and an outer surface and between inner and outer surface an essentially isotropic support layer with a sponge-like, open-pored, microporous structure free of macrovoids and adjacent to this support layer on the outer surface a dense separation layer with a thickness between 1.0 and 3.5 &#x3bc;m. The membrane has a porosity in the range of greater than 35% to less than 50% by volume and a permeance for COof 20-60 mol/(h&#xb7;m&#xb7;bar), a gas separation factor &#x3b1;(CO/N) of at least 5 and a selectivity CO/anesthetic agents of at least 150. The process for producing this membrane is based on a thermally induced phase separation process in which process a homogeneous solution of a poly(4-methyl-1-pentene) in a solvent system containing components A and B is formed, wherein component A is a strong solvent and component B a weak non-solvent for the polymer component. After formation of a hollow fiber the hollow fiber is cooled in a liquid cooling medium to form a hollow fiber membrane. The concentration of the polymer component in the solution may be in the range from 42.5 to 45.8 wt.-% and the hollow fiber leaving the die runs through a gap between die and cooling medium with a gap length in the range of 5-30 mm.

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Neuss, Germany

Ina Voigt