Polysulfone-based blood treatment membrane and method of producing the same
A polysulfone-based blood treatment membrane that exhibits excellent antioxidant properties, excellent long-term storage stability, and a practical strength, and ensures high productivity, a polysulfone-based blood treatment membrane that exhibits excellent antioxidant properties and long-term storage stability, rarely allows endotoxins to enter a treatment liquid, exhibits a practical strength, and ensures high productivity, and a method of producing the same. A polysulfone-based blood treatment membrane includes a polysulfone-based resin, a hydrophilic polymer, and a lipophilic antioxidant, the membrane containing the lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane, and the total amount of the lipophilic antioxidant present on the surface of the membrane being 4 to 25 mg per gram of the membrane. Another polysulfone-based blood treatment membrane contains a lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane, wherein the inner surface of the membrane has a TOF-SIMS normalized peak intensity of the lipophilic antioxidant of 1.8.times.10.sup.-4 or more, and the outer surface of the membrane has a TOF-SIMS normalized peak intensity of the lipophilic antioxidant of 2.4.times.10.sup.-4 or more. A method of producing a polysulfone-based blood treatment membrane that includes a polysulfone-based resin, a hydrophilic polymer, and a lipophilic antioxidant includes producing a membrane intermediate that contains the lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane intermediate, and heating the membrane intermediate at 100 to 180.degree. C. for 0.1 to 360 minutes in a dry state.
1. A polysulfone-based blood treatment membrane that is a permselective membrane comprising a polysulfone-based resin, a hydrophilic polymer and a lipophilic antioxidant, in which the membrane contains the lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane, and the total amount of the lipophilic antioxidant present on the surface of the membrane is 4 to 25 mg per gram of the membrane, wherein the membrane is in the form of hollow fibers having inner and outer surfaces, the membrane having a skin layer on the inner surface of the hollow fiber and a porous structure between the skin layer and the outer surface.
2. The polysulfone-based blood treatment membrane according to claim 1 , wherein the membrane has TOF-SIMS normalized peak intensities, that is an index indicating the concentration of the lipophilic antioxidant on the surface of the membrane, of 1.4×10 −4 or more for the inner surface of the membrane, and of 1.8×10 −4 or more for the outer surface of the membrane.
3. The polysulfone-based blood treatment membrane according to claim 1 , wherein the lipophilic antioxidant is a lipophilic vitamin.
4. A polysulfone-based permselective membrane comprising a polysulfone-based resin, a hydrophilic polymer, and a lipophilic antioxidant, and produced using a membrane-forming raw spinning solution including the polysulfone-based resin, the hydrophilic polymer, the lipophilic antioxidant, and a solvent, in which the membrane is produced by obtaining a membrane intermediate that contains the lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane intermediate, and then heat-treating the membrane intermediate at 100 to 180° C. for 0.1 to 360 minutes in a dry state with a water content equal to or less than saturation water content, so that the membrane contains the lipophilic antioxidant in an amount of 30 to 76 mg per gram of the membrane, and the total amount of the lipophilic antioxidant present on the surface of the membrane is 4 to 25 mg per gram of the membrane.