Mitsubishi Rayon Company, Limited

Masashi Teramachi

Masakazu Minagawa

Toshinori Sumi

Kei Murase

Hiroyuki Fujiki

Yasuo Hiromoto

Masaki Kurashina

Shusaku Takahashi

Takahito Ooba

A hollow porous membrane of the present invention comprises a plurality of porous membrane layers, at least two layers of which are formed using a thermoplastic resin (a) having a mass average molecular weight of 500,000 or more, and the hollow porous membrane having a bursting pressure of 200 kPa or more when an internal pressure is applied and exhibiting virus removal performance of LRV 4 or more in the case of using MS2 phage as a test bacterium.

Hollow porous membrane

Disclosed is a process for production of a porous membrane that includes the steps of layering a film-forming dope that contains a polymer (A) that forms a membrane base, a polyvinylpyrrolidone (B) and a solvent (C) into a single layer or two or more layers; immersing the film-forming dope in a solidifying fluid that is a non-solvent with respect to the polymer (A) and is a good solvent with respect to the polyvinylpyrrolidone (B); and removing the polyvinylpyrrolidone (B), wherein the polyvinylpyrrolidone (B) has a K value of 50 to 80, a mass ratio r of the polyvinylpyrrolidone (B) to the polymer (A) is 0.5 or more and less than 1, and the viscosity of the film-forming dope at a membrane production temperature is 100 to 500 Pa&#xb7;s. Accordingly, by using an appropriate amount of a low-molecular-weight hydrophilic polymer capable of being easily removed, it is possible to produce a porous membrane of a three-dimensional network structure in which macrovoids are suppressed, having high water permeability and superior filtration performance.

Process for production of porous membrane

A hollow porous membrane with a reduced cost and excellent separation characteristic, water permeability, and mechanical strength and a process of producing the hollow porous membrane with an excellent adhesive property between a support and a porous membrane layer at a low cost are provided. The hollow porous membrane includes a porous membrane layer in which dense layers are disposed in the vicinities of an outer surface and an inner surface. In the process of producing the hollow porous membrane, membrane-forming dopes of a first membrane-forming dope and a second membrane-forming dope, which contain the material of the porous membrane layer and a solvent, are successively applied and stacked onto the outer circumferential surface of a hollow support and the applied membrane-forming dopes are simultaneously coagulated. In the process of producing the hollow porous membrane, a porous membrane layer is formed by applying a membrane-forming dope containing a material of the porous membrane layer and a solvent to the outer circumferential surface of the hollow support and coagulating the applied dope, and a hollow braid obtained by circularly knitting a yarn formed of multi-filaments is used as the support.

Hollow porous membrane and process for producing the same

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Toyohashi, Japan

Masashi Teramachi