HOLLOW FIBER MEMBRANE MADE BY MELT-SPINNING POLYOLEFIN/FILLER COMPOSITION

摘要

A porous, annular, polyolefin, fiber membrane of 150 to 300 .mu.m inside diameter and 10 to 150 .mu.m wall thickness, having on the inner wall side thereof a tight layer of intimately bound fine polyolefin particles and on the outer wall side thereof a porous texture of fine polyolefin particles bound in chains and containing fine pores extending continuously from the inner wall side to the outer wall side. The membrane is formed by mixing a polyolefin, an organic filler uniformly dispersible in the polyolefin under conditions capable of melting the polyolefin and readily soluble in an extractant to be used, and a crystal seed forming agent; discharging the resultant mixture in a molten state through an annular spinning orifice and, at the same time, introducing an inert gas into the hollow center of the discharged tube of the mixture: advancing the discharged tube into contact with a cooling and solidifying liquid incapable of melting the polyolefin thereby cooling and solidifying the tube; and subsequently bringing the cooled and solidified tube into contact with an extractant incapable of disolving the polyolefin, thereby extracting the organic filler out of the tube.