The present inventive concept relates to a method of preparing an ion-exchange membrane using a chemical modification and an ion-exchange membrane prepared thereby. More specifically, the present inventive concept relates to a method of preparing an ion-exchange membrane, which is characterized by modifying sulfonic acid groups of a perfluorinated sulfonic acid electrolyte membrane with carboxyl groups and includes chlorinating sulfonic acid groups of a perfluorinated sulfonic acid electrolyte membrane; nitrilating the chlorinated electrolyte membrane; and hydrolyzing the nitrilated electrolyte membrane, and an ion-exchange membrane chemically modified thereby.

Provided are an inexpensive, high-quality, permeation-side flow path material that is suitable for use in spiral membrane elements and enables the improvement of productivity, a method for producing such a permeation-side flow path material, and a membrane element having such a permeation-side flow path material. Provided are (a) a permeation-side flow path material for use in a spiral membrane element, the permeation-side flow path material comprising a resin sheet comprising a plurality of ridge portions 31 formed parallel to one another; and a plurality of openings 32 formed between each pair of the ridge portions 31, (b) a method for producing such a permeation-side flow path material, and (c) a membrane element having such a permeation-side flow path material.

Provided are an inexpensive, high-quality, permeation-side flow path material that is suitable for use in spiral membrane elements and enables the improvement of productivity, a method for producing such a permeation-side flow path material, and a membrane element having such a permeation-side flow path material. Provided are (a) a permeation-side flow path material for use in a spiral membrane element, the permeation-side flow path material comprising a resin sheet comprising a plurality of ridge portions 31 formed parallel to one another; and a plurality of openings 32 formed between each pair of the ridge portions 31, (b) a method for producing such a permeation-side flow path material, and (c) a membrane element having such a permeation-side flow path material.

A spunbonded nonwoven fabric includes thermoplastic fibers, wherein the thermoplastic fibers are conjugate fibers in which a low-melting polymer having a melting point lower by 10 to 140 C. than that of a high-melting polymer is provided around the high-melting polymer, the spunbonded nonwoven fabric has a non-pressure bonding portion having an apparent density of 0.20 to 0.60 g/cm.sup.3, when a long axis length of a fiber cross section of the non-pressure bonding portion is a and a short axis length thereof is b, a fiber flatness a/b is 1.5 to 5, and an air permeability satisfies formula (1):

[air permeability (cc/cm.sup.2.Math.sec)]520exp(0.0236[basis weight (g/m.sup.2)]2.85[apparent density (g/cm.sup.3)])(1).

A porous ultra-thin polymer film has a film thickness of 10 nm-1000 nm. A method of producing the porous ultra-thin polymer film includes dissolving two types of mutually-immiscible polymers in a first solvent in an arbitrary proportion to obtain a solution; applying the solution onto a substrate and then removing the first solvent from the solution applied onto the substrate to obtain a phase-separated ultra-thin polymer film that has been phase-separated into a sea-island structure; and immersing the ultra-thin polymer film in a second solvent which is a good solvent for the polymer of the island parts but a poor solvent for a polymer other than the island parts to remove the island parts, thereby obtaining a porous ultra-thin polymer film.

A porous ultra-thin polymer film has a film thickness of 10 nm-1000 nm. A method of producing the porous ultra-thin polymer film includes dissolving two types of mutually-immiscible polymers in a first solvent in an arbitrary proportion to obtain a solution; applying the solution onto a substrate and then removing the first solvent from the solution applied onto the substrate to obtain a phase-separated ultra-thin polymer film that has been phase-separated into a sea-island structure; and immersing the ultra-thin polymer film in a second solvent which is a good solvent for the polymer of the island parts but a poor solvent for a polymer other than the island parts to remove the island parts, thereby obtaining a porous ultra-thin polymer film.

Process for reducing the fouling of a surface O, wherein an aqueous solution S of at least one polymer P comprising styrene and at least one ester E of (meth)acrylic acid and polyethylene oxide in a molar ratio of 0.05:1 to 50:1 is applied to said surface O.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.

The present disclosure relates to hollow fiber tangential flow filters, including hollow fiber tangential flow depth filters, for various applications, including bioprocessing and pharmaceutical applications, systems employing such filters, and methods of filtration using the same.