Method of making membranes for gas separation and the composite membranes
AssigneeThe Research Foundation of State University of New York
InventorsIsrael Cabasso, Kevin A. Lundy
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Abstract
Composite membranes suitable for separating gas mixtures are made by in situ crosslinking of aminoorganofunctional polysiloxane, 1 to 9 mol percent aminosiloxane units, with diisocyanate on the surface of a highly porous polymer substrate, such as polysulfone. Using the crosslinked polysiloxane as a gutter layer, a gas separating entity can be coated on the gutter layer to make a double layer composite membrane which has a higher separation factor than the crosslinked polysiloxane and can be used effectively for flat sheet membranes, as well as, hollow fiber membranes.
Claims35
A method for making a composite suitable for increasing the oxygen gas content of an oxygen-nitrogen gas mixture by passing the mixture through the composite, consisting essentially of
- coating an aminoorganofunctional polysiloxane on at least one surface of a 20 to 250 .mu.m thick, highly porous, polymer substrate, where the polysiloxane is applied in a thickness sufficient to provide a cured membrane having a thickness of 0.1 .mu.m to 20 .mu.m, the polysiloxane consisting essentially of a random copolymer of from 1 to 9 mol percent aminosiloxane units having primary aminoorganofunctionality and 91 to 99 mol percent other repeating siloxane units
- contacting the polysiloxane coated on the substrate with a solution of a non-isocyanate-reactive organic solvent and diisocyanate for a sufficient time to cause a crosslinked membrane to form, where the weight ratio of the polysiloxane to the diisocyanate is in an inverse relationship to the permeability coefficient of the composite.
A double layer composite membrane suitable for separating gases consisting essentially of a 20 to 250 .mu.m thick highly porous polymer substrate having tightly adhered thereto a gutter layer of a highly gas permeable rubber obtained by crosslinking an aminoorganofunctional polysiloxane having from 1 to 9 mol percent primary aminoorganofunctionality bearing siloxane units and 91 to 99 mol percent other siloxane units, and tightly adhered and overcoating the gutter layer is a gas separating entity.
Dependencies are inferred from the claim text.