Abstract A method is disclosed for the preparation (by the utilization of a proper solvent system) of dry asymmetric membranes comprising a porous layer of interconnected crystals of polymer material. Membranes of many polymer materials may be optionally prepared either with or without a dense surface layer as one face thereof. In either case the porous layer is structured with graded porosity. A three-component casting solution is prepared containing the polymer, a first good volatile solvent for the polymer and (relative to the first solvent) a poor less-volatile solvent for the polymer, which is miscible with the good solvent. A membrane is cast at room temperature, allowed to desolvate at room temperature for a short time and is then immersed in a precipitating agent, that is miscible with both the aforementioned solvents but is a non-solvent for the polymer. The membrane is then permitted to dry.
A METHOD FOR THE PREPARATION OF ASYMMETRIC POLYMER MEMBRANES COMPRISING THE STEPS OF: A. DISSOLVING AT LEAST ABOUT 5 PERCENT BY WEIGHT OF POLYARYLENE OXIDE IN A SOLVENT SYSTEM, SAID SOLVENT SYSTEM CONSISTING OF CHLOROFORM AND DICHLOROBENZENE, B. CASTING A LAYER OF THE POLYARYLENE OXIDE SOLUTION SO FORMED ON A FLAT CLEAN SURFACE IN A THICKNESS RANGING FROM ABOUT 5 TO 25 MILS, WHEREBY A SINGLE MAJOR SURFACE IS EXPOSED, C. PERMITTING DESOLVATION TO OCCURE FOR LESS THAN 1 MINUTE, D. IMMERSING SAID LAYER IN METHANOL, E. REMOVING THE ASYMMETRIC POLYARYLENE OXIDE MEMBRANE SO
Claim 2
Independent Claim
94 words
A METHOD FOR THE PREPARATION OF ASYMMETRIC POLYMER MEMBRANES COMPRISING THE STEPS OF: A. DISSOLVING AT LEAST ABOUT 5 PERCENT BY WEIGHT OF POLYARYLENE OXIDE IN A SOLVENT SYSTEM, SAID SOLVENT SYSTEM CONSISTING OF CHLOROFORM AND DICHLOROBENZENE, B. CASTING A LAYER OF THE POLYARYLENE OXIDE SOLUTION SO FORMED ON A FLAT CLEAN SURFACE IN A THICKNESS RANGING FROM ABOUT 5 TO 25 MILS, WHEREBY A SINGLE MAJOR SURFACE IS EXPOSED, C. PERMITTING DESOLVATION TO OCCURE FOR LESS THAN 1 MINUTE, D. IMMERSING SAID LAYER IN METHANOL, E. REMOVING THE ASYMMETRIC POLYARYLENE OXIDE MEMBRANE SO
Claim 3
Dependent Claim
13 words
The method recited in claim 1 wherein the polymer material is polyxylylene oxide.