| abstract |
Provided are a porous hollow fiber membrane suitable for filtration applications and the like, having both high stopping power and water permeability, and excellent in mechanical strength, and a method for stably producing the same. Specifically, using a hollow fiber molding nozzle having two or more annular discharge ports arranged concentrically, heat from the annular discharge port is different from each other from adjacent annular discharge ports. Each melt-kneaded product of plastic resin and organic liquid is ejected in an annular shape, and is subjected to annular multilayer melt extrusion, cooled and solidified to form a hollow fiber, and then the organic liquid is extracted and removed from the cooled and solidified hollow fiber. In the method for producing a porous multilayer hollow fiber membrane, the molten kneaded product discharged from at least one annular discharge port is kneaded with inorganic fine powder in addition to the thermoplastic resin and the organic liquid, and is cooled and solidified. A method for producing a porous multilayer hollow fiber membrane, wherein inorganic fine powder is also extracted and removed later in addition to an organic liquid. |