Process for producing composite membranes
AssigneeAir Products and Chemicals, Inc.
InventorsJacob A. Van't Hof, Pushpinder S. Puri, Stephen C. Lynch, Albert A. Brooks, Daniel T. Diggs
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Abstract
A process is provided for fabricating composite membranes by coating a porous substrate with a solution of selective polymer. A reserve of non-solvent medium is incorporated in the substrate pore network which allows the substrate to be successfully coated with a polymer solution formulated in a solvent medium which is also a solvent for the substrate material.
Claims20
A process for producing a composite gas separation membrane which comprises:
- a) forming a porous polymeric substrate;
- b) providing a rescue of a non-solvent aqueous medium in the pore network of the substrate which serves to protect said substrate from subsequently applied coating solutions which contain solvents for the substrate;
- c) applying a coating solution onto a surface of the substrate, wherein said coating solution comprises a permselective polymer material formulated in a solvent medium which is also a solvent for the polymeric substrate, to form a coated substrate;
- d) bringing said coated substrate into contact with a coagulation liquid which is miscible with both the non-solvent medium and the solvent medium used above;
- and
- e) removing said coagulation liquid along with said non-solvent and solvent media to form a composite membrane.
The process of claim I wherein said porous polymeric substrate is formed from a polymer selected from the group consisting of polysulfones, polyethersulfones, polyetherimides, polyphenylene oxides, polyamides, polycarbonates, polyesters, polyethers, polyacrylonitriles, polyimides, polyamidimides, polyvinylidene fluoride and mixtures thereof including copolymers.
In a process for producing a composite gas separation membrane wherein a porous polymeric substrate is coated with permselective polymer material in a solvent and the solvent removed, the improvement for producing said composite membrane wherein the solvent for the permselective polymer material is a solvent for the porous polymeric substrate which comprises:
- a) providing a non-solvent aqueous medium within the pore network of the porous polymeric substrate thereby forming a pore filled, porous polymeric substrate;
- b) coating the pore filled, porous polymeric substrate with said permselective polymer material in a solvent which is also a solvent for the porous polymeric substrate to form a coated, pore filled, porous polymeric substrate;
- c) contacting the coated, pore filled, porous polymeric substrate with a coagulation liquid which is miscible with both the non-solvent aqueous medium and the solvent;
- and
- d) removing the coagulation liquid along with at least a portion of the non
- solvent aqueous medium and the solvent, thereby forming said composite membrane.
Dependencies are inferred from the claim text.