Akzo N.v.

3m Innovative Properties Company

Membrana Gmbh

Akzo Nobel N.v.

Em Innovative Properties Company

Wolfgang Ansorge

Oliver Schuster

Gustav Dunweg

Quan Huang

Lothar Steinfeld

Friedbert Wechs

Karl Bauer

Michael Schmidt

Florentin Michael Wilfart

Gustav Duweg

Phung Ngoc Duong

Ralf Hornscheidt

Jan Haelssig

Andreas Jungheim

Ina Voigt

Klaus Muller

Ernst Spindler

Lother Steinfeld

Ngoc-Phung Duong

Richard Krüger

Martin Rütering

Klaus Dombrowski

Phung Duong

Hydrophobic flat membrane made from a vinylidene fluoride polymer with a wall, a first surface, and a second surface. The membrane has on its first surface a network structure with open pores and on its second surface a continuous skin in which pores are formed, and adjacent to the skin of the second surface a supporting layer with an isotropic pore structure across the wall thickness, wherein the supporting layer extends over at least 80% of the wall thickness and wherein the pores of the supporting layer have an average diameter of less than 1 &#x3bc;m. The weight average of the molecular weight Mof the vinylidene fluoride polymer lies in the range from 300 000 to 500 000 daltons, and the polydispersivity M/Mis greater than 5.5. The pores in the skin of the second surface have a closed perimeter in the plane of the skin and an average ratio of the extension in the direction of the longest axis thereof to the extension in the direction of the shortest axis thereof of at most 5. The pores in the first surface and second surface have an essentially isotropic distribution of their orientation. The porosity of the membrane lies in the range from 50 to 90 vol. % and the wall thickness in the range from 50 to 300 &#x3bc;m. The membrane has a maximum separating pore diameter din the range from 0.05 to 1.5 &#x3bc;m.

Microporous polyvinyl fluoride planar membrane and production thereof

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

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.

Hollow fiber membrane for use in an anesthetic circuit

The invention relates to a hollow-fiber membrane for ultrafiltration made from a hydrophobic aromatic sulfone polymer and at least one hydrophilic polymer, the membrane having an open-pore separating layer on the lumen side, an adjoining supporting layer with asymmetric, sponge-like pore structure without finger pores and an outer layer adjoining the supporting layer towards the outer surface. The separating layer has a cutoff between 20 000 and 200 000 daltons, a thickness of max. 10% of the membrane thickness and an essentially isotropic pore structure. The size of the pores in the supporting layer initially increases up to a zone with maximum pore size, and then decreases towards the outer layer, and the outer layer exhibits a thickness of 10 to 30% of the wall thickness and an essentially isotropic pore structure. The mean size of the pores in the outer layer is larger than in the separating layer, but smaller than in the supporting layer. The wall thickness of the hollow-fiber membrane lies in the range from 100 to 450 &#x3bc;m. The invention relates furthermore to a method for the production of these hollow-fiber membranes.

Ultrafiltration membrane

Method for producing this membrane from a casting solution comprising the hydrophobic first sulfone polymer and the hydrophilic second polymer in a solvent system, the method comprising the steps of pouring the casting solution, conditioned to a molding temperature, onto a carrier to form a film, which carrier has a temperature that is higher in comparison to the molding temperature, conveying the film through a climate-controlled zone, initiating the coagulation in a coagulation bath for the formation of a membrane structure, withdrawing the membrane structure from the carrier with a speed that is increased in comparison to the carrier speed, stabilizing, extracting, and subsequently drying the membrane.

Microfiltration membrane with improved filtration properties

A dialysis membrane in the form of a hollow fiber with a continuous internal cavity is made of cellulose acetate or a cellulose acetate derivative. The membrane has a maximum screen coefficient of 0.04 for albumin with a molecular weight of 68,000. A dialysis membrane in the form of a hollow fiber with a continuous internal cavity may be made in a process using a spinning solution containing an organic carboxylic acid and a cavity-forming liquid. Modification agents and/or water are optionally added and the solution is extruded through a spinneret suitable for the manufacture of hollow fibers. The precipitation of the resultant dialysis membrane and the usual further aftertreatment take place in a precipitation bath. The organic carboxylic acid preferably is acetic acid and the precipitation bath preferably is a dilute acetic acid.

Process for manufacturing cellulose acetate membranes

The invention relates to a process for removing a lumen filler and/or undesired auxiliary processing agents from hollow fibers or hollow fiber membranes by extraction with supercritical gases. The invention likewise relates to the hollow fibers or hollow fiber membranes freed of a lumen filler and/or undesired auxiliary processing agents by this process.

Process for cleaning hollow fibers

A dialysis membrane in the form of a hollow fiber with a continuous internal cavity is made of cellulose acetate or a cellulose acetate derivative. The hollow fiber is made by using a gas to form the internal hollow cavity. A dialysis membrane in the form of a hollow fiber with a continuous hollow cavity may be made in a process using a spinning solution containing an organic carboxylic acid. Modification agents can be added to the solution and the solution extruded through a spinneret suitable for manufacturing hollow fibers, while an internal medium is introduced simultaneously into the internal cavity of the forming hollow fiber. The precipitation of the dialysis membrane thus formed and an ordinary further aftertreatment take place subsequently in a precipitation bath. The hollow fiber is made by using a gas as the internal medium to form the internal cavity.

Dialysis membrane made of cellulose acetate

A dialysis membrane in the form of a hollow fiber with a continuous internal cavity is made of cellulose acetate or a cellulose acetate derivative. The membrane has a maximum sieving coefficient of 0.04 for albumin with a molecular weight of 68,000. A dialysis membrane in the form of a hollow fiber with a continuous internal cavity may be made in a process using a spinning solution containing an organic carboxylic acid and a cavity-forming liquid. Modification agents and/or water are optionally added and the solution is extruded through a spinneret suitable for the manufacture of hollow fibers. The precipitation of the resultant dialysis membrane and the usual further aftertreatment take place in a precipitation bath. The organic carboxylic acid preferably is acetic acid and the precipitation bath preferably is a diluted acetic acid.

Cellulose acetate membranes

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Essen, Germany

Wolfgang Ansorge