Hollow fiber membrane spinning nozzle, and method for manufacturing hollow fiber membrane

Abstract

A hollow fiber membrane-spinning nozzle that spins a hollow fiber membrane having a porous membrane layer and a support is provided in which the nozzle includes a resin flow channel through which a membrane-forming resin solution forming the porous membrane layer flows, the resin flow channel includes a liquid storage section that stores the membrane-forming resin solution and a shaping section that shapes the membrane-forming resin solution in a cylindrical shape and satisfies at least one of conditions (a) to (c): (a) the resin flow channel is disposed to cause the membrane-forming resin solution to branch and merge; (b) a delay means for delaying the flow of the membrane-forming resin solution is disposed in the resin flow channel; and (c) the liquid storage section or the shaping section includes branching and merging means for the membrane-forming resin solution therein.

1 . A hollow fiber membrane-spinning nozzle, comprising:
 a resin flow channel through which a membrane-forming resin solution forming a porous membrane layer flows,   wherein the hollow fiber membrane-spinning nozzle spins a hollow fiber membrane,   the hollow fiber membrane comprises the porous membrane layer and a support,   the resin flow channel comprises a liquid storage section for storing the membrane-forming resin solution and a shaping section for shaping the membrane-forming resin solution in a cylindrical shape, and   the hollow fiber membrane-spinning nozzle satisfies at least one condition selected from the group consisting of (a), (b), and (c):   (a) the resin flow channel is disposed to cause the membrane-forming resin solution to branch and merge;   (b) delay means for delaying a flow of the membrane-forming resin solution is disposed in the resin flow channel; and   (c) the liquid storage section or the shaping section comprises branching and merging means for the membrane-forming resin solution therein.   
     
     
         2 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the liquid storage section has an annular cross-sectional shape.   
     
     
         3 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the resin flow channel comprises two or more merging portions in which the membrane-forming resin solution merges.   
     
     
         4 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the liquid storage section or the shaping section comprises the branching and merging means for the membrane-forming resin solution therein, and   the branching and merging means is a porous element which is disposed in the liquid storage section and through which the membrane-forming resin solution passes.   
     
     
         5 . The hollow fiber membrane-spinning nozzle according to  claim 4 ,
 wherein the porous element is a porous member having a three-dimensional mesh structure.   
     
     
         6 . The hollow fiber membrane-spinning nozzle according to  claim 4 ,
 wherein the porous element is a cylindrical porous element.   
     
     
         7 . The hollow fiber membrane-spinning nozzle according to  claim 6 ,
 wherein the cylindrical porous element is disposed to cause the membrane-forming resin solution to pass from an outer circumferential surface to an inner circumferential surface.   
     
     
         8 . The hollow fiber membrane-spinning nozzle according to  claim 4 ,
 wherein the porous element has a disk-like shape.   
     
     
         9 . The hollow fiber membrane-spinning nozzle according to  claim 4 ,
 wherein the porous element is made of a sintered compact of metal.   
     
     
         10 . The hollow fiber membrane-spinning nozzle according to  claim 9 ,
 wherein the porous element is made of a sintered compact of metal particulates or a sintered compact of metallic meshes.   
     
     
         11 . The hollow fiber membrane-spinning nozzle according to  claim 1 , further comprising:
 a circular support passage through which the support passes,   wherein a diameter of the circular support passage is of from 95% to 200% of an outer diameter of the support.   
     
     
         12 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the support is made of a twisted string or a braided string.   
     
     
         13 . The hollow fiber membrane-spinning nozzle according to  claim 4 ,
 wherein the hollow fiber membrane-spinning nozzle comprises two or more resin flow channels having two or more liquid storage sections for storing the membrane-forming resin solution and the shaping section, and   the branching and merging means is the porous element disposed in each of the two or more liquid storage sections.   
     
     
         14 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein computed number of merging flows in an annular cross-sectional shape of the hollow fiber membrane is equal to or more than 50.   
     
     
         15 . The hollow fiber membrane-spinning nozzle according to  claim 4 , further comprising:
 an ejection hole through which the membrane-forming resin solution is ejected,   wherein a pressure loss when the membrane-forming resin solution passes through the porous element is greater than a pressure loss until the membrane-forming resin solution reaches the porous element and a pressure loss until the membrane-forming resin solution reaches the ejection hole after passing through the porous element.   
     
     
         16 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the resin flow channel is disposed to cause the membrane-forming resin solution to branch and merge,   the resin flow channel comprises a liquid storage section that is divided into liquid storage chambers of two or more stages, and   two or more supply channels for supplying the membrane-forming resin solution from a top-stage liquid storage chamber to a lower-stage liquid storage chamber are disposed along an outer wall of the liquid storage section.   
     
     
         17 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the liquid storage section or the shaping section comprises the branching and merging means for the membrane-forming resin solution therein, and   the branching and merging means is a filler layer filled with particles and disposed in the liquid storage section.   
     
     
         18 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the resin flow channel is disposed to cause the membrane-forming resin solution to branch and merge,   the resin flow channel comprises the liquid storage section that is vertically divided into two or more stages, and   a top-stage liquid storage section and a lower-stage liquid storage section communicate with a resin supply section.   
     
     
         19 . The hollow fiber membrane-spinning nozzle according to  claim 18 ,
 wherein the liquid storage section is divided into three or more stages, and   a resin supply section causing the n-th-stage (where n is a natural number) liquid storage section and the (n+1)-th-stage liquid storage section to communicate with each other and a resin supply section causing the (n+1)-th-stage liquid storage section and the (n+2)-th-stage liquid storage section to communicate with each other are arranged at positions shifted along a circumferential direction of the liquid storage section.   
     
     
         20 . The hollow fiber membrane-spinning nozzle according to  claim 18 ,
 wherein the resin supply section is arranged with a constant angle interval in a circumferential direction of the liquid storage section about a central axis of the shaping section sequentially from the top-stage liquid storage section.   
     
     
         21 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the resin flow channel is provided with delay means for delaying the flow of the membrane-forming resin solution, and   the delay means is a meandering section that causes the membrane-forming resin solution to vertically meander between the liquid storage section and the shaping section.   
     
     
         22 . The hollow fiber membrane-spinning nozzle according to  claim 1 ,
 wherein the resin flow channel is disposed to cause the membrane-forming resin solution to branch and merge, and   the resin flow channel is a weir extending from one wall surface of the liquid storage section to other wall surface and regulating the flow of the membrane-forming resin solution in the liquid storage section so that the flow revolves.   
     
     
         23 . A method of manufacturing a hollow fiber membrane comprising a hollow porous membrane layer and a support, the method comprising:
 spinning a hollow fiber membrane from a membrane-forming resin solution, thereby obtaining a spun hollow fiber membrane;   coagulating the spun hollow fiber membrane with a coagulating liquid, thereby obtaining a coagulated hollow fiber membrane;   removing a solvent from the coagulated hollow fiber membrane;   decomposing an additive in the hollow fiber membrane from which the solvent has been removed and washing the hollow fiber membrane, thereby obtaining a washed hollow fiber membrane; and   drying the washed hollow fiber membrane,   wherein the spinning comprises spinning the hollow fiber membrane from the membrane-forming resin solution with the hollow fiber membrane-spinning nozzle according to  claim 1 .   
     
     
         24 . The method according to  claim 23 ,
 wherein an outer diameter of the hollow fiber membrane spun in the spinning is of from 0.5 mm to 5.0 mm, and   a value d/dh obtained by dividing an outer diameter d of the hollow fiber membrane by an inner diameter dh thereof is of from 1.3 to 5.0.   
     
     
         25 . The method according to  claim 23 ,
 wherein computed number of merging flows in an annular cross-sectional shape of the hollow fiber membrane spun in the spinning is equal to or more than 50.