An object of the present invention is to provide a porous hollow-fiber membrane satisfying both high strength and high pure-water permeation performance and at the same time, having high bending resistance. The present invention relates to a porous hollow-fiber membrane including a fluororesin-based polymer, in which the porous hollow-fiber membrane has a columnar texture oriented in a longitudinal direction of the porous hollow-fiber membrane and when a photograph of a cross-section parallel to the longitudinal direction of the porous hollow-fiber membrane is binarized into a structure portion and a void portion, the following 1) and 2) are satisfied: 1) a proportion of an area of the void portion is from 20 to 50%, and 2) a value obtained by dividing a total of peripheral lengths of the void portions by a total of areas of the void portions is 2.0 m.sup.1 or less.

When the porous membrane, which has two surfaces of a surface A and a surface C, is equally divided in the thickness direction of the porous membrane into three layers of a first layer including the surface A, a second layer that is a central layer in the thickness direction, and a third layer including the surface C, an average trunk size of the third layer is larger than an average trunk size of the second layer, and when a continuous layer from the surface A having a thickness of 10 m in the first layer is a first layer component, a continuous layer component having a thickness of 10 m and an average trunk size smaller than an average trunk size of the first layer component is present in the first layer, the second layer, and the third layer other than the first layer component.

A semipermeable asymmetric hollow fiber membrane is provided, based on a hydrophobic polymer, such as polyethersulfone or polysulfone, and on a hydrophilic polymer, such as PVP. The PVP polymer comprises a high molecular weight component and a low molecular weight component. The membrane has a significantly improved permeability and selectivity, based on its structure, composition, and the method of manufacture of the membrane A process for manufacturing such a membrane by a solvent phase inversion spinning process is also provided.

Systems and methods can be used to produce fibers with external corrugations, internal corrugations, or both. These fibers can be used, for example, in hollow fiber membrane modules.

The present invention relates to a hollow fiber membrane including, sequentially from the center: a first layer having a high-density sponge structure including pores with a size of 1 nm or less; a second layer including a finger-shaped structure; and a third layer having a low-density sponge structure including pores with a size of 10 to 1,000 m, and to a method for producing the hollow fiber membrane.

A method for the manufacture of ceramic hollow fiber membranes in a spinning process by using a spinning mass, comprising the steps: providing a spinning mass formulation; providing a secondary phase; adding the secondary phase to the spinning mass formulation; manufacturing the ceramic hollow fiber membranes in a spinning process.

A hollow fiber membrane of the present invention is a hollow fiber membrane having an outer surface and an inner surface, wherein the inner surface has a zebra stripe pattern in which dense portions and porous portions are alternately formed in the longitudinal direction, and the outer surface has a maximum pore size of about 1 m or less (about 1 m), and wherein the hollow fiber membrane has a water permeability (flux) of about 1,300 LMH/bar to about 5,000 LMH/bar.

A virus removal membrane is formed from a hydrophilized synthetic polymer, in which, when a solution containing gold colloids having a diameter of 20 nm is applied through a primary surface to the virus removal membrane to allow the virus removal membrane to capture the gold colloids for measurement of brightness in a cross section of the virus removal membrane, a value obtained by dividing a standard deviation of a value of an area of a spectrum of variation in the brightness by an average of the value of the area is 0.01 or more and 1.5 or less; and a thickness of a portion, where gold colloids having a diameter of 20 nm or more and 30 nm or less are captured, in the cross section of the virus removal membrane in a wet state is 10 m or more and 30 m or less.

The problem addressed by the present invention is to provide a separation membrane with superior permeation performance and separation performance and having few occurrences of defects. The present invention relates to a separation membrane wherein: the separation membrane has a layer (I) with a thickness of 0.5-100 m; letting, in a cross-section in the direction of thickness of the layer (I), region a be a region with a depth of 50-150 nm from a surface (surface A), region b a region with a depth of 50-150 nm from the other surface (surface B), and region c a region with a thickness of 100 nm where the depth from both surfaces is the same, the average pore diameter Pa for region a and the average pore diameter Pb for region b are both 0.3-3.0 nm and the average pore diameter Pc for region c is 3.0 nm or less; and the percentage of open area Ha for region a, the percentage of open area Hb for region b, and the percentage of open area Hc for region c satisfy the following equations. 2Hc<Ha 2Hc<Hb

The present disclosure relates to a dialyzer comprising a bundle of semipermeable hollow fiber membranes which is suitable for blood purification, wherein the dialyzer has an increased ability to remove larger molecules while at the same time it is able to effectively remove small uremic toxins and efficiently retain albumin and larger proteins. The invention also relates to using said dialyzer in hemodialysis.