SEMI-PERMEABLE MEMBRANES WITH AN INTERNAL DISCRIMINATING REGION

摘要

The invention is a semi-permeable membrane which comprises a polymeric matrix with two porous surfaces and a region which functions to separate one or more gases from one or more other gases. A composition is disclosed that is useful for the preparation of a bisphenol-based polycarbonate membrane wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated, preferably Cl or Br. The composition includes (i) a bisphenol-based polycarbonate wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated, wherein the halogen is Cl or Br, (ii) a solvent for such polycarbonate, and (iii) a non-solvent for such polycarbonate. A process is described wherein the composition is heated and extruded into a shape suitable for membrane use such as a hollow fiber. The formed membrane is then passed through a quench zone wherein the mixture undergoes phase separation, and the solvent non-solvent are removed and a discriminating region capable of separating oxygen from nitrogen is formed. The membranes of this invention exhibit excellent separation factors and flux. Such membranes are less prone to being damaged due to handling and exposure to contaminants due to the internal region which affects the separation, as the porous surfaces function to protect such region.