Chemical Systems Incorporated

Puropore Inc.

Nuclepore Corporation

Robert E Kesting

A casting solution of two nylons in formic acid, e.g., high molecular weight extrusion grade Nylon 66 homopolymer [.eta.] about 2 or higher, and nylon multipolymer 66, 610, 6 as a strengthening polymer and gelation promoter, when cast by either the dry or wet phase inversion processes, results in highly unexpected membranes of superior strength, flexibility, and uniformity, suitable for use in microfiltration and ultrafiltration.

High strength nylon blend membranes

The discovery that highly anisotropic membranes, e.g. with a degree of anisotropy of five can for the very first time be produced by the dry phase inversion process by a very specific combination of polymers, solvent and non-solvent, optionally along with plasticizers and modifiers, all of which separately are known in membrane technology, the polymers consisting essentially of cellulose nitrate and cellulose nitrate-cellulose acetate mixed ester polymers, the solvent being methyl formate, propylene oxide, or mixtures thereof, and the non-solvents being isopropyl alcohol, t-butyl alcohol or mixtures thereof, is disclosed.

Highly anisotropic membranes

Membrane forming polymers are converted to hydrophilic polymeric membranes by (a) grafting a polyoxyethylene chain to a membrane forming polymer structure and thereafter forming a membrane; (b) coating a membrane with a polymer to which a polyoxyethylene chain has been grafted; or (c) grafting in situ a polyoxyethylene chain to a formed membrane polymer.

Polyoxyethylene grafted membrane materials with grafting links derived

Microfiltration membranes are described comprising 10% to 50% cyanoethylated polysaccharide ether polymers blended with 50% to 90% polymers of cellulose nitrate, cellulose acetate or mixtures of the two. These membranes are flexible and strong and can be readily pleated for use in cartridge filters as well as used flat in conventional single- or multi-plate holders. They are also more thermally stable than conventional 'mixed ester' (cellulose nitrate/cellulose acetate) membranes.

Flexible microporous cellulosic membranes and methods of formation and

A dense hollow fiber cellulosic membrane which possesses outstanding permeability and strength characteristics and the method of preparation thereof is disclosed.

Process for spinning dense hollow fiber cellulosic membrane

Integral, skinned and unskinned, microporous microfiltration and ultrafiltration, electrophoresis membranes having high void volumes (above 50% void) composed of polycarbonates and copolymers of polycarbonates with polyalkylene oxides and the dry process for producing such membranes are disclosed.

Dry process for forming polycarbonate membranes

A new composition, cellulose acetate-chlorobutyrate pyridinium salt, which has superior biodegradation resistance and polymer membrane forming characteristics and related compositions.

Nonbiodegradable polymers

A dry-wet process for forming interiorally asymmetric hollow fiber cellulose acetate membranes is disclosed.

Process for spinning dry-fiber cellulose acetate hollow fiber membranes

Microporous membrane filters composed of polyesters derived from aromatic dibasic acids and especially polytetramethylene terephthalate are produced. These membranes are produced by a polymer assisted phase inversion process involving casting a solution of the polyester and assisting polymer to form a film, evaporating the solvent to form a membrane having inchoate micropores filled with the assisting polymer and subsequently at least partially leaching out the assiting polymer.

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Irvine, CA, United States of America

Robert E Kesting