Kuraray Co., Ltd.

Shuzo Yamashita

Syuji Kawai

Hirokuni Tanii

Akira Kubotsu

Taku Tanaka

Koichi Takakura

Kyoichiro Shibatani

Shiro Nagata

Kiochi Takakura

Kiyokazu Imai

There is provided a hollow fiber membrane of ethylene-vinyl alcohol copolymer which is produced by a process comprising extruding a spinning solution of an ethylene-vinyl alcohol copolymer in a solvent selected from the group consisting of dimethylsulfoxide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone and mixtures thereof through a hollow fiber spinneret while a liquid coagulant is introduced into a central aperture of said spinneret, passing the spun fiber through a gaseous atmosphere in a manner such that the fiber is drawn 0.5 to 20 times its extrusion rate and then coagulating said fiber in a coagulating bath at a temperature within the range satisfying the following relationship:

Ethylene-vinyl alcohol hollow fiber membrane and method for the

A hollow fiber membrane made of an ethylene-vinyl alcohol copolymer is provided, which is characterized in that, when observed in a dry state with an electron microscope, the hollow fiber membrane has at least one dense, active layer (or skin layer) on the inside and/or outside surface thereof and further a three-layered structure comprising two layers respectively contacting the inside and outside surfaces and each consisting of a plurality of particles bonded together and having particle sizes of 0.01 to 2 microns and a substantially particle-free homogeneous layer lying between the two layers. A method of producing such hollow fiber membranes is also provided comprising spinning a spinning solution prepared by dissolving an ethylene-vinyl alcohol copolymer in a solvent mainly consisting of dimethyl sulfoxide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone or a mixture of these through a spinneret for hollow fiber production while simultaneously introducing a coagulating liquid through the central aperture of said spinneret, passing the spun fiber through a gaseous atmosphere such that the fiber is drawn to 3 to 30 times its original length, and coagulating the fiber in a coagulation bath at a temperature within the range specified below:

Method of producing ethylene-vinyl alcohol copolymer hollow fiber

A hollow fiber membrane made of an ethylene-vinyl alcohol copolymer is provided, which is characterized in that, when observed in a dry state with an electron microscope, the hollow fiber membrane has at least one dense, active layer (or skin layer) on the inside and/or outside surface thereof and further a three-layered structure comprising two layers respectively contacting the inside and outside surfaces and each consisting of a plurality of particles bonded together and having particle sizes of 0.01 to 2 microns and a substantially particle-free homogeneous layer lying between the two layers. A method of producing such hollow fiber membranes is also provided comprising spinning a spinning solution prepared by dissolving an ethylene-vinyl alcohol copolymer in a solvent mainly consisting of dimethyl sulfoxide, dimethylacetamide, pyrrolidone, N-methylpyrrolidone or a mixture of these through a spinneret for hollow fiber production while simultaneously introducing a coagulating liquid through the central aperture of said spinneret, passing the spun fiber through a gaseous atmosphere such that the fiber is drawn to 3 to 30 times its extrusion rate, and coagulating the fiber in a coagulation bath at a temperature within the range specified below:

Ethylene-vinyl alcohol copolymer hollow fiber membranes and method of

Materials for forming a hydrogel when contacted with water having improved anti-thrombogenic properties and a highly improved mechanical strength are obtained by the copolymerization of a free radical-polymerizable vinyl monomer capable of forming a hydrophilic polymer and a hydrophobic macromolecular compound having a chain-terminated polymerizable double bond and a molecular weight of 1,000 to 100,000.

Hydrophilic-hydrophobic graft copolymers for self-reinforcing hydrogels

There is described an ethylene-vinyl alcohol copolymer membrane comprising at least a skin layer on its surface and a porous layer supporting the skin layer. The porous layer, when the membrane is observed in the dry state with an electron microscope, contains vacuoles or voids, which present a mono- or multi-layer structure and have straight-line lengths corresponding to 20-99% of the whole thickness of the membrane. In addition, the polymer portion of the porous layer has micropores with an average pore diameter of 0.1-5 microns and the membrane has a porosity of 60-90%.

Ethylene-vinyl alcohol copolymer membrane and a method for producing the

A membrane made of a composition containing essentially two kinds of ethylene-vinyl alcohol copolymers with different ethylene unit contents and the membrane has such a microstructure that there are at least one active layer and a porous layer thereunder, the porous layer comprises mono- or multi-layer of a plurality of cylindrical voids and a plurality of spherical voids therein and the membrane is of a porosity of 70 to 95%.

Ethylene-vinyl alcohol membranes having improved properties and a method

Ethylene-vinyl alcohol copolymer membranes characterized by constituent particles having an average diameter within the range of from 100 to 10,000 Angstrom units, determined under an electron microscope for the dry membrane, bonded to each other, wherein the membrane is substantially free from pores in excess of from 2 microns in diameter. Such a membrane has a permeability to water of 10 to 200 .times. 10.sup.-16 cm.sup.2 and to vitamin B.sub.12 of not less than 0.8 .times. 10.sup.-7 cm.sup.2 per second, and being of particular value as a membrane for the dialysis of blood. The membrane is obtained by dissolving an ethylenevinyl alcohol copolymer in a solvent consisting essentially of dimethylsulfoxide or dimethylacetamide and causing the resulting solution to coagulate from an aqueous coagulation bath under mild conditions such that the coagulation time as defined in the specification is not less than 3 seconds.

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Kurashiki, Japan

Shuzo Yamashita