PREPARATION OF PVDF(POLYVINYLIDENE FLUORIDE) HOLLOW FIBER MEMBRANE BY MELT SPINNING AND STRETCHING PROCESS

摘要

A new preparation method is provided to prepare a porous PVDF(polyvinylidene fluoride) hollow fiber membrane effectively while the preparation method is based on the stretching process. A method for the preparation of a porous PVDF(polyvinylidene fluoride) hollow fiber membrane comprises the steps of: (a) melt spinning and cooling PVDF with a melt index of 0.5 g/10 min or less to produce a PVDF hollow fiber precursor; (b) annealing the PVDF hollow fiber precursor to produce non-stretched PVDF hollow fibers; and (c) cold stretching the non-stretched PVDF hollow fibers at a temperature of 40 deg.C or less by applying a deformation rate of 0.3 to 20 %/sec and a stretching ratio of 30 to 200% to the non-stretched PVDF hollow fibers. The method comprises applying a draft ratio of 50 to 500 to the PVDF hollow fiber precursor in the process of cooling the PVDF hollow fiber precursor in the step(a). The method further comprises a step of thermally setting PVDF hollow fiber membranes obtained in the step(c).