Akzo N.v.

Membrana Gmbh

Em Innovative Properties Company

3m Innovative Properties Company

Karl Bauer

Oliver Schuster

Heinz-Dieter Sluma

Quan Huang

Alfons Leeb

Wolfgang Ansorge

Phung Ngoc Duong

Robert Weizenhofer

Robert Weinzenhofer

Ngoc-Phung Duong

Phung Duong

Hydrophobic hollow-fiber membrane made from a vinylidene fluoride polymer with a wall and a wall thickness, an outer surface on its outer side, an inner surface on its inner side and facing its lumen and adjacent to the inner surface a supporting layer having a structure that is substantially isotropic across the wall thickness, the supporting layer extending over at least 80% of the wall thickness and comprising pores having an average diameter of less than 1 &#x3bc;m, and wherein the hollow-fiber membrane has pores on its outer surface and on its inner surface, characterized in that the vinylidene fluoride polymer has a weight-average molecular weight Min the range from 550 000 to 700 000 daltons and a polydispersivity greater than 3.0; the pores in the outer and in the inner surface are formed like islands and have a maximum ratio of their longitudinal extension to the transverse extension of 10; the porosity lies in the range from 50 to 90 vol. %, the wall thickness in the range from 50 to 300 &#x3bc;m, and the diameter of the lumen in the range from 100 to 500 &#x3bc;m; and the hollow-fiber membrane has a maximum separating pore diameter din the range from 0.3 to 0.7 &#x3bc;m, determined according to the bubble point method.

Microporous polyvinylidene fluoride membrane

The invention relates to a hydrophobic, integrally asymmetrical hollow-fiber membrane made of a vinylidene fluoride homopolymer or copolymer, wherein the wall of the membrane has a microporous supporting layer having a sponge-like, open-pored, essentially isotropic pore structure without finger pores, the supporting layer extending across at least 90% of the wall thickness and having pores with an average diameter of less than 0.5 &#x3bc;m. The hollow-fiber membrane is characterized in that it has a separating layer adjacent to the supporting layer on its outer surface and that it has an outer surface with a homogeneous, uniform structure without pores, a porosity in the range from 40 to 80 vol. %, a wall thickness from 25 to 100 &#x3bc;m, a diameter of the lumen of the hollow-fiber membrane from 100 to 500 &#x3bc;m, a permeability for nitrogen of at least 25 ml/(cm&#xb7;min&#xb7;bar), and an elongation at break of at least 250%. The invention further relates to a method for producing hollow-fiber membranes of this type.

Hydrophobic ozone-stable membrane made of polyvinylidene fluoride

A multilayer membrane for separating gas mixtures includes a polymer supporting membrane with a voids volume of more than 50% and a coating of two or more separating layers made of two or more different polymers. A hollow capillary serving as the supporting membrane is guided through the central bore of a spinneret. The spinneret has one or several concentric annular slits and/or annular grooves, through each of which a solution of one of the polymers forming the separating layers is applied to the supporting membrane. The spinneret terminates in a sealed chamber in which the solvent or solvents of the polymer solutions is/are evaporated and removed. The coated supporting membrane is drawn out of the chamber and wound up, possibly following aftertreatment with heat and/or liquids.

Gas separation membrane

Method of making a multilayer capillary membrane

Growing community of inventors

Dammbach, Germany

Karl Bauer