Patent ID: 9095819
Filing Date: 2015-08-04
Classification: B01D

Abstract:
1. A method for producing a hollow fiber membrane from a composition, said composition comprising, based on the weight of said composition, from 40% to 60% by weight of a polymer matrix, from 20% to 30% by weight of an organic mixed solution, and from 20% to 40% by weight of a water-soluble substance; wherein: said polymer matrix is selected from the group consisting of polyurethane and polyvinyl chloride; said organic mixed solution comprises, based on the weight of said organic mixed solution, from 60% to 90% by weight of a first liquid and from 10% to 40% by weight of a second liquid; said first liquid is selected from the group consisting of dimethylacetamide, dimethylformamide, and dimethylsulfoxide; said second liquid is selected from the group consisting of 1,3-butanediol, 1,4-butanediol, and a mixture thereof; said water-soluble substance is selected from the group consisting of a first water-soluble compound, a second water-soluble compound, and a mixture thereof; said first water-soluble compound is selected from the group consisting of lithium chloride, potassium chloride, sodium chloride, calcium chloride, urea, sucrose, sodium glutamate, and a mixture thereof; and said second water-soluble compound is selected from the group consisting of polyethylene oxide, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl alcohol, and a mixture thereof; the method comprising the steps of: a) mixing said first liquid with said second liquid to yield said an organic mixed solution; b)(i) if said first water-soluble compound is used as said water-soluble substance, mixing said first water-soluble compound with said organic mixed solution to obtain a first mixture, and then mixing said first mixture with said polymer matrix to obtain said composition; b)(ii) if said second water-soluble compound is used as said water-soluble substance, mixing said polymer matrix with said water-soluble polymer to obtain a second mixture, and then mixing said second mixture with said organic mixed solution to obtain said composition; or, b)(iii) if said first and second water-soluble compounds are both used as said water-soluble substance, mixing said first and second mixtures to obtain said composition; c) melting said composition at a melting temperature of said polymer matrix ±30° C., and extruding said composition to obtain an extrudant in a shape of a hollow filament; and d) drawing said extrudant through an air gap of 15-100 mm in a first bath, subjecting said extrudant to a second bath and a third bath to solidify said polymer matrix in said extrudant, and washing said extrudant with water for more than 2 h to dissolve said organic mixed solution and said water-soluble substance out of said extrudant, whereby forming pores on said extrudant and obtaining said hollow fiber membrane; said first bath being a steam bath or air bath, said second bath being a cold water bath, and said third bath being an air bath, water bath, oil bath, or steam bath at a temperature ≧20° C.