Abstract: The porous hollow-fiber membrane of the present invention comprises a fluororesin polymer, and has columnar structures oriented in the longitudinal direction thereof. In the porous hollow-fiber membrane, molecular chains of the fluororesin polymer have been oriented in the longitudinal direction of the porous hollow-fiber membrane and have an average value ? of Raman orientation parameter of 1.5-4.0.

Abstract: 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?1 or less.

Abstract: The porous hollow-fiber membrane of the present invention comprises a fluororesin polymer, and has columnar structures oriented in the longitudinal direction thereof. In the porous hollow-fiber membrane, molecular chains of the fluororesin polymer have been oriented in the longitudinal direction of the porous hollow-fiber membrane and have an average value ? of Raman orientation parameter of 1.5-4.0.

Abstract: An object of the present invention is to provide a separation membrane having high mechanical strength and being less likely to cause clogging and capable of continuously maintaining high water permeation performance. The present invention relates to a separation membrane characterized in that the average diameter D1 of a spherical structure in a region within 10 ?m from a first surface in a separation membrane having a spherical structure layer formed of a thermoplastic resin and the average diameter D2 of a spherical structure in a region of 10 ?m to 20 ?m from a second surface satisfy the relational expression of D1>D2 and the average diameter D1 and the average diameter D3 of a spherical structure in a third region satisfy the relational expression of 1.10<D1/D3<4.00.

Abstract: The present invention provides a porous hollow fiber membrane that has both high strength and high pure water permeability, and that exhibits excellent thermal deformation resistance. The present invention is related to a porous hollow fiber membrane containing a fluororesin-based polymer, and a manufacturing method of the membrane comprises a drawing step and a relaxing step. The porous hollow fiber membrane is characterized in that: the molecular chain of the polymer is oriented in the longitudinal direction of the hollow fiber membrane; and at the same time internal distortion of oriented non-crystalline chains, which is disadvantageous in terms of entropy, is alleviated.

Abstract: 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?1 or less.

Abstract: The present invention provides a porous hollow fiber membrane that has both high strength and high pure water permeability, and that exhibits excellent thermal deformation resistance. The present invention is related to a porous hollow fiber membrane containing a fluororesin-based polymer, and a manufacturing method of the membrane comprises a drawing step and a relaxing step. The porous hollow fiber membrane is characterized in that: the molecular chain of the polymer is oriented in the longitudinal direction of the hollow fiber membrane; and at the same time internal distortion of oriented non-crystalline chains, which is disadvantageous in terms of entropy, is alleviated.

Abstract: An object of the present invention is to provide a stretching method for producing a membrane of narrowed hollow fibers while suppressing hollow fiber crushing (flattening), using a simple stretching process. The present invention relates to a method for manufacturing a hollow fiber membrane that performs narrowing of diameter of a hollow fiber by stretching, that is, includes a step of narrowing diameter of a hollow fiber by stretching the hollow fiber that has been subjected to a spinning step, using rolls each of which is formed with a groove.

Abstract: An object of the present invention is to provide a porous hollow-fiber membrane having high strength while maintaining high pure-water permeation performance. A porous hollow-fiber membrane of the present invention is 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 a molecular chain of the fluororesin-based polymer is oriented in the longitudinal direction of the porous hollow-fiber membrane.

Abstract: An object of the present invention is to provide a porous hollow-fiber membrane having high strength while maintaining high pure-water permeation performance. A porous hollow-fiber membrane of the present invention is 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 a molecular chain of the fluororesin-based polymer is oriented in the longitudinal direction of the porous hollow-fiber membrane.

Abstract: An object of the present invention is to provide a separation membrane having high mechanical strength and being less likely to cause clogging and capable of continuously maintaining high water permeation performance. The present invention relates to a separation membrane characterized in that the average diameter D1 of a spherical structure in a region within 10 ?m from a first surface in a separation membrane having a spherical structure layer formed of a thermoplastic resin and the average diameter D2 of a spherical structure in a region of 10 ?m to 20 ?m from a second surface satisfy the relational expression of D1>D2 and the average diameter D1 and the average diameter D3 of a spherical structure in a third region satisfy the relational expression of 1.10<D1/D3<4.00.

Abstract: A separation membrane including a separation-functional layer is provided, wherein the separation-functional layer contains a polyvinylidene fluoride-type resin having a melt viscosity of 3,300 Pa·s or more, and also the separation-functional layer has a three-dimensional network structure. A separation membrane is provided having high virus removal performance, high pure water permeability, and high physical durability and high chemical strength, which can also be used in the field of water treatment.

Abstract: A separation membrane including a separation-functional layer is provided, wherein the separation-functional layer contains a polyvinylidene fluoride-type resin having a melt viscosity of 3,300 Pa·s or more, and also the separation-functional layer has a three-dimensional network structure. A separation membrane is provided having high virus removal performance, high pure water permeability, and high physical durability and high chemical strength, which can also be used in the field of water treatment.

Abstract: A method for manufacturing a porous membrane including a three-dimensional network structure and a spherical structure is provided. The method includes forming a porous membrane having a spherical structure, applying a resin solution onto at least one surface of the porous membrane having the spherical structure, followed by immersing the membrane in a solidification liquid, thereby forming the three-dimensional network structure on at least one surface of a porous membrane having the spherical structure.

Abstract: A method of producing a hollow fiber membrane includes discharging a polyvinylidene fluoride solution comprising a polyvinylidene fluoride resin and a poor solvent at a temperature above a phase separation temperature into a cooling bath at a temperature below the phase separation temperature to coagulate the polyvinylidene fluoride resin. The hollow fiber membrane comprises a polyvinylidene fluoride resin having spherical structures that have an average diameter in the range of 0.3 to 30 ?m.

Abstract: A method of producing a hollow fiber membrane includes discharging a polyvinylidene fluoride solution comprising a polyvinylidene fluoride resin and a poor solvent at a temperature above a phase separation temperature into a cooling bath at a temperature below the phase separation temperature to coagulate the polyvinylidene fluoride resin. The hollow fiber membrane comprises a polyvinylidene fluoride resin having spherical structures that have an average diameter in the range of 0.3 to 30 ?m.

Abstract: The object of the present invention is to provide a porous membrane having a high strength and excellent water permeability and rejection properties. The porous membrane of the present invention has both a three-dimensional network structure and a spherical structure. The porous membrane of the present invention is suitably used for water treatment membranes, battery separators, charged membranes, fuel cells, blood purification membranes, and the like.

Abstract: A method of producing a hollow fiber membrane includes discharging a polyvinylidene fluoride solution comprising a polyvinylidene fluoride resin and a poor solvent at a temperature above a phase separation temperature into a cooling bath at a temperature below the phase separation temperature to coagulate the polyvinylidene fluoride resin. The hollow fiber membrane comprises a polyvinylidene fluoride resin having spherical structures that have an average diameter in the range of 0.3 to 30 ?m.

Abstract: A method of producing a hollow fiber membrane includes discharging a polyvinylidene fluoride solution comprising a polyvinylidene fluoride resin and a poor solvent at a temperature above a phase separation temperature into a cooling bath at a temperature below the phase separation temperature to coagulate the polyvinylidene fluoride resin. The hollow fiber membrane comprises a polyvinylidene fluoride resin having spherical structures that have an average diameter in the range of 0.3 to 30 ?m.

Abstract: A method of producing a hollow fiber membrane includes discharging a polyvinylidene fluoride solution comprising a polyvinylidene fluoride resin and a poor solvent at a temperature above a phase separation temperature into a cooling bath at a temperature below the phase separation temperature to coagulate the polyvinylidene fluoride resin. The hollow fiber membrane comprises a polyvinylidene fluoride resin having spherical structures that have an average diameter in the range of 0.3 to 30 &mgr;m.