PREPARATION OF ASYMMETRIC POLYMER MEMBRANES
First Claim
1. 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
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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.
43 Citations
2 Claims
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1. 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
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2. The method recited in claim 1 wherein the polymer material is polyxylylene oxide.
Specification