Hollow fibre membrane extrusion
AssigneeMemtec Limited
InventorsClinton V. Kopp, Robert J. W. Streeton, Paul S. Khoo
Life of this patent
Estimating the term…
Abstract
Extrusion of hollow membranes is improved by coextruding a coating fluid layer about the extrudate of heated polymer solution with its interior lumen forming extrudate. The coating fluid is disposed between the forming hollow fiber and a cooling fluid, and controls the rate of heat transfer to afford superior control over the structure and form of the hollow fiber produced in the invention. The coating fluid is typically the same material as the cooling fluid, and often is the same material as the solvent for the polymer in the heated polymer solution.
Claims18
In the process of extruding through an extrusion head polymeric hollow fibers by coextrusion of a heated polymer solution, a lumen-forming fluid and a cooling fluid, forming said heated polymer solution into a hollow fiber shape, cooling to effect a non-equilibrium liquid-liquid phase separation to form a bi-continuous matrix comprising a polymer-rich phase and a solvent-rich phase, further cooling to solidify the polymer in the form defined by said polymer-rich phase and removing the solvent from the polymer, the improvement comprising:
- coextruding a coating fluid in a continuous layer disposed around said hollow fiber shape between said heated polymer solution and said cooling fluid, at a temperature substantially equal to that of said heated polymer solution, to control the rate of heat transfer from said heated polymer solution into said cooling fluid.
Dependencies are inferred from the claim text.