초록 ▼

A dope for forming membranes and the resulting asymmetric gas separation membranes are disclosed, the membranes having graded density skins which exhibit improved permeability characteristics and increased failure pressure strength. The membranes are produced from a process utilizing membrane formin

A dope for forming membranes and the resulting asymmetric gas separation membranes are disclosed, the membranes having graded density skins which exhibit improved permeability characteristics and increased failure pressure strength. The membranes are produced from a process utilizing membrane forming dopes of complexing solvent systems formulated from two non-solvents and one or more solvents. The non-solvents are chosen one each, from non-solvents grouped according to non-solvent strength, i.e., one strong non-solvent and one weak non-solvent which are combined with one or more solvents in an acid:base complex solvent system for dissolving high weight percent total solids of membrane forming polymers. The process for forming the membranes is also disclosed.

대표청구항 ▼

A process for forming a hollow-fiber, asymmetric, substantially macrovoid-free membrane with potential for gas separation which exhibits increased failure pressure strength, the membrane being comprised of a glassy hydrophobic polymer, the process, comprising: (a) dissolving the polymer in a solvent

A process for forming a hollow-fiber, asymmetric, substantially macrovoid-free membrane with potential for gas separation which exhibits increased failure pressure strength, the membrane being comprised of a glassy hydrophobic polymer, the process, comprising: (a) dissolving the polymer in a solvent system comprised of a strong non-solvent, a weak non-solvent Lewis acid, a solvent Lewis base and a complex formed of Lewis acid and Lewis base, wherein the solvent system has a Hildebrand solubility parameter within about 1.5 cal0.5/cm1.5 of the Hildebrand solubility parameter of the polymer, to form a spinning dope containing at least 30% by weight total solids of polymer; (b) spinning the dope through the orifice of a tube-in-orifice type spinnerette; (c) injecting coagulation fluid through the tube of the spinnerette; (d) coagulating the spun dope in a coagulation medium and forming the membrane; (e) desolvating the formed membrane by washing the membrane in a polar medium; and (f) drying the membrane at a temperature from about ambient to about 50°C. below the glass transition temperature of the polymer.