Abstract: A sheet-shaped hollow fiber membrane module includes a casing having a flat shape, the casing including a supply port and a discharge port, and a plurality of hollow fiber membranes accommodated inside the casing. The casing includes a plurality of the supply ports on one main surface of the casing and a plurality of the discharge ports on the other main surface of the casing, at least one of the plurality of the supply ports is closable, and at least one of the plurality of the discharge ports is closable. Each of the plurality of hollow fiber membranes includes a first opening at one end of the hollow fiber membrane and a second opening at the other end of the hollow fiber membrane, and the first opening and the second opening communicate with an outside of the casing and do not communicate with an inside of the casing.

Abstract: A sheet-shaped hollow fiber membrane module includes a casing having a flat shape, the casing including a supply port and a discharge port, and a plurality of hollow fiber membranes accommodated inside the casing. The casing includes a plurality of the supply ports on one main surface of the casing and a plurality of the discharge ports on the other main surface of the casing, at least one of the plurality of the supply ports is closable, and at least one of the plurality of the discharge ports is closable. Each of the plurality of hollow fiber membranes includes a first opening at one end of the hollow fiber membrane and a second opening at the other end of the hollow fiber membrane, and the first opening and the second opening communicate with an outside of the casing and do not communicate with an inside of the casing.

Abstract: An object of the present invention is to provide a hollow-fiber ultrafiltration membrane that can be used in treatment in various aqueous fluids such as water purification, beverage treatment, seawater clarification, and that has excellent fractionation characteristics and permeability, while deterioration of its performance due to passage of time is minimized, and that has excellent recovery of the membrane-separation characteristics by cleaning. The main feature of the hollow-fiber ultrafiltration membrane of the present invention is that the specific surface area of the membrane surface to which raw water is supplied falls within the range from not less than 1.10 to not greater than 1.55. The present invention also provides a process for producing a hollow-fiber ultrafiltration membrane, wherein a heat treatment is conducted under the condition that the membrane having a residual organic solvent content of not greater than 300 mg/g.

Abstract: This disclosure relates to an anisotropic polyvinylidene fluoride hollow fiber microporous membrane containing a polyvinylidene fluoride resin. The hollow fiber microporous membrane does not include macrovoids, and has mainly a net-like structure. In addition, the hollow fiber microporous membrane has a dense outer layer on an outer surface, and a homogeneous bulk layer that is internally adjacent to the outer layer and has a coarser structure than the outer layer. The porosity of the bulk layer is at least 1.5 times the membrane surface porosity of the outer layer. The dense structure of the outer layer changes substantially discontinuously into the coarse structure of the bulk layer.

Abstract: An object of the present invention is to provide a hollow-fiber ultrafiltration membrane that can be used in treatment in various aqueous fluids such as water purification, beverage treatment, seawater clarification, and that has excellent fractionation characteristics and permeability, while deterioration of its performance due to passage of time is minimized, and that has excellent recovery of the membrane-separation characteristics by cleaning. The main feature of the hollow-fiber ultrafiltration membrane of the present invention is that the specific surface area of the membrane surface to which raw water is supplied falls within the range from not less than 1.10 to not greater than 1.55. The present invention also provides a process for producing a hollow-fiber ultrafiltration membrane, wherein a heat treatment is conducted under the condition that the membrane having a residual organic solvent content of not greater than 300 mg/g.

Abstract: Problems: To provide a polyvinylidene fluoride microporous membrane which has high water permeability and separation performance and is excellent in mechanical and chemical strength; and a process for producing the film. Means for Solving Problems: An anisotropic polyvinylidene fluoride hollow fiber microporous membrane characterized in that the porosity of the cross-sectional bulk layer is higher than the membrane surface porosity of the outer layer and that in the cross section of the membrane, the dense microstructure of the outer surface changes substantially discontinuously into the coarse structure of the bulk layer.

Abstract: The present invention relates to a composite semipermeable membrane, which is useful as a reverse osmosis membrane or a nano-filtration membrane and comprises a polysulfone porous support membrane and a polyamide ultrathin layer formed on one of the surfaces of the porous support membrane, the composite membrane having the characteristic that in the infrared absorption spectrum obtained from the surface of a polyamide ultrathin layer of the composite semipermeable membrane, the ratio T (=Aa/As) of absorption intensity Aa at the absorption peak revealing C═O of polyamide in the region of 1600-1700 cm−1 to absorption intensity As at the absorption peak revealing polysulfone at a wavenumber around 1586 cm−1 is at least 0.05 and not higher than 3.

Abstract: The present invention relates to a composite semipermeable membrane, which is useful as a reverse osmosis membrane or a nano-filtration membrane and comprises a polysulfone porous support membrane and a polyamide ultrathin layer formed on one of the surfaces of the porous support membrane, the composite membrane having the characteristic that in the infrared absorption spectrum obtained from the surface of a polyamide ultrathin layer of the composite semipermeable membrane, the ratio T (=Aa/As) of absorption intensity Aa at the absorption peak revealing C═O of polyamide in the region of 1600-1700 cm−1 to absorption intensity As at the absorption peak revealing polysulfone at a wavenumber around 1586 cm−1 is at least 0.05 and not higher than.