Highly selective asymmetric membranes for gas separation and method for the manufacture thereof
AssigneeInstitut Francais du Petrole
InventorRene Avrillon
Life of this patent
Estimating the term…
Abstract
A method for preparing highly selective asymmetric polymer membranes for gas separation is provided wherein the polymer is dissolved in a volatile solvent containing dioxane, and a film or tube extrusion of the polymer solution is formed. Some of the solvent is evaporated and the film or tube is contacted with a coagulant comprising acetic acid and water. The film or the tube is then dried.
Claims10
A method for the manufacture of an asymmetric polyimide or copolyimide polymer membrane for gas separation, said polyimide or copolyimide being derived from diphenyldi(trifluoromethyl)methane 3,4,3',4'-tetracarboxylic acid dianhydride and either a monoaromatic metadiamine or a mixture of monoaromatic metadiamines, said method comprising the following steps:
- (a) dissolving said polyimide or copolyimide in a volatile solvent containing at least 85% by weight of 1,4 dioxane and 0 to 15% by weight of N-methyl 2-pyrrolidone, N,N-dimethylacetamide and/or gamma-butyrolactone,
- (b) applying a film of a solution of polyimide or copolyimide of step (a) to a support or extruding a tube of a solution of polyimide or copolyimide of step (a),
- (c) partially evaporating the solvent from the film or tube,
- (d) bringing the film or tube into contact with a liquid coagulant comprising a mixture of between 15 and 99% by weight of acetic acid and between 1 and 85% by weight of water, and
- (e) drying the coagulated film or tube.
Dependencies are inferred from the claim text.