| abstract |
In a method for producing hollow fibernmembranes which comprises melt kneading a mixturencomprising polyvinylidene fluoride and an organicnliquid or a mixture comprising polyvinylidene fluoride,nan organic liquid and an inorganic fine powder,nextruding the kneaded mixture to form hollow fibers,nand extracting the organic liquid or the organic liquidnand the inorganic fine powder from the hollow fibers,nwhich includes the steps of drawing the hollow fibersnbefore or after termination of the extraction and thennshrinking the fibers. According to this method, it isnpossible to stably produce hollow fiber membranesnhaving dense pores and having a high water permeationnperformance, excellent endurance and stain resistance,nand which are suitable for filtration uses such asnremoval of turbidity of water. |