초록 ▼

A method for preparing an asymmetric, semi-permeable membrane containing a uniform microporous structure for gas and liquid separation, including forming a dense separation on one major surface of a microporous support structure. The microporous support structure is initially formed as a solid unita

A method for preparing an asymmetric, semi-permeable membrane containing a uniform microporous structure for gas and liquid separation, including forming a dense separation on one major surface of a microporous support structure. The microporous support structure is initially formed as a solid unitary film, fiber or sheet by the simultaneous extrusion of at least two streams of heat-plastified polymeric materials including at least two differentially soluble polymeric materials. The separation layer can be formed on the support structure prior to or after the soluble polymeric material has been dissolved out of, as by leaching from the solid support structure to form the microporous support for the separation layer. Preparation in this manner greatly reduces the tendency to form undesiralbe pinholes in the membrane.

대표청구항 ▼

A method for preparing an asymmetric membrane comprising a separation layer and a microporous support layer comprising providing a membrane support structure by: forming a lamellar polymeric composition by dividing and reorienting a plurality of adjacent layers of polymeric materials, each layer com

A method for preparing an asymmetric membrane comprising a separation layer and a microporous support layer comprising providing a membrane support structure by: forming a lamellar polymeric composition by dividing and reorienting a plurality of adjacent layers of polymeric materials, each layer comprising at least two different polymeric materials and having a thickness of from 0.03 to 5 microns to form discrete domains of said polymeric materials of random orientation, at least one of said different polymeric materials having a preferential solubility in a selected solvent with respect to at least one other of said different polymeric materials; forming a melt composition of said lamellar polymeric composition into a thin solid support structure; and converting said thin solid support structure to an asymmetric membrane by: (A) providing a separation layer on one major surface of said support structure and treating said separation layer-coated support structure with an extraction medium which is substantially inert with respect to said separation layer to remove said preferentially soluble polymeric material to provide an asymmetric membrane structure comprising at least one separation layer and at least one porous support layer; or (B) contacting said solid support structure with an extraction medium which has a preferential solubility for at least one of said at least two different polymeric materials, whereby said preferentially soluble polymeric material is removed from said solid support structure to form a porous structure and providing a separation layer on one major surface of said porous structure.