Method for manufacturing asymmetric polyvinlylidenefluoride hollow fiber membrane and hollow fiber membrane manufactured therefrom

Abstract

The present invention relates to a method for manufacturing an asymmetric polyvinlylidenefluoride (PVDF) hollow fiber membrane, which enables effective mixing of PVDF and a diluent without using separate inorganic fine powder, such as silica; in which a PVDF hollow fiber membrane is manufactured using a thermally induced phase separation method having an advantage of allowing easy obtaining of a separation membrane of consistent quality due to a key factor in controlling the phase separation in the two-substance mixture system of the polymer and the diluent being temperature, which is a manufacturing variable that is relatively simple and easy to control; in which a technique is applied for producing a temperature difference between the outer and the inner surfaces of a PVDF hollow fiber, and therefore, finally an asymmetric structure is expressed in which the inner surface side and the outer surface side of the PVDF hollow fiber have mutually different pore sizes and distributions; and which, even when an extraction process and a drawing process are applied, achieves a higher tensile strength and a larger average pore size, and thus higher porosity and water permeability than conventional hollow fiber membranes, since inorganic fine powder is not included. The asymmetric PVDF hollow fiber membrane has a pore symmetry index, defined as the ratio between the pore area on the outer surface and the pore area on the inner surface, of 0.1-0.8 and has superior water permeability and tensile strength unlike a PVDF separation membrane manufactured by the existing method.

Description

Technical field [0001] This application claims priority for Korean Patent Application No. 10-2013-0064164 filed in the Republic of Korea on June 4, 2013, the disclosure of which is incorporated herein by reference. [0002] The present disclosure relates to an effective method of manufacturing asymmetric polyvinylidene fluoride (PVDF) hollow fiber membranes, thereby preparing particles of PVDF and diluents to enable PVDF to be made without additional use of inorganic fine powders such as silica. It is effectively mixed with the diluent, and the phase separation of PVDF and the diluent is thermally induced by providing a temperature difference between the inner surface and the outer surface of the hollow fiber during spinning, thereby realizing the inner surface side and the outer surface side of the hollow fiber Asymmetric structure with different pore size and distribution. The present disclosure also relates to an asymmetric PVDF hollow fiber membrane, which has a pore symmetry...

AI Technical Summary

Problems solved by technology

[0012] The disadvantages of PVDF hollow fiber membranes prepared according to the prior art are that they are symmetrical hollow fiber membranes with the same pore size and distribution inside and outside the hollow fibers, and long kneading zones when extruders are used for homogeneous mixing The device should be used to ensure sufficient stirring time in order to overcome the low compatibility between PVDF and diluent, and the reliability of kneading of PVDF and diluent should be ensured by, for example, dosing raw materials to the extruder

In addition, it is disadvantageous in that extraction must be performed by adding inorganic fine powder such as hydrophobic silica for effective mixing of diluents, and that stretching and shrinkage are necessary

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