PROCESS FOR PREPARING HOLLOW MICROPOROUS POLYPROPYLENE FIBERS

摘要

The present invention provides a process for preparing hollow microporous polypropylene fibers having an oxygen gas permeability of at least 35 cc/cm2.min at 10 psi. The high gas permeability is achieved by melt spinning isotactic polypropylene at a temperature of at least 230.degree.C to form precursor hollow fibers having an average inner diameter of at least 140 microns, and an average inner diameter to average wall thickness ratio of from about 8:1 to about 40:1, annealing the precursor fibers at a temperature of about 50.degree.C to not greater than 165.degree.C, and subsequently cold stretching, hot stretching and then heat setting the microporus fibers. The resulting hollow microporous fibers exhibit an average inner diameter of at least 100 microns.