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AssigneeAsahi Kasei Kogyo Kabushiki Kaisha
InventorsMorikazu Miura, Yoshiaki Nitadori, Akira Kiguchi, Shigemi Mukaiyama
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A polysulfone membrane for purifying blood having excellent compatibility with blood and the process producing the membrane are disclosed. The membrane comprises a mixed polymer phase of a graft copolymer and/or block copolymer having a molecular weight of 3.times.10.sup.5 daltons or more and comprising (A) a hydrophilic segment and (B) a hydrophobic segment (exclusive of polysulfone) in a total amount of from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, with the monomer unit ratio (A/B) between the segments A and B being from 0.5 to 5. The copolymer is preferably a graft copolymer where the hydrophilic segment is a polyvinylpyrrolidone segment and the hydrophobic segment is a polystyrene segment. The membrane can be prepared by applying a wet film formation process to a dope containing an appropriate solvent of the mixed polymer, such as N,N-dimethylacetamide. The membrane for purifying blood reduces cumbersomeness in the washing of the coagulated membrane during the film formation process and allows recovery of the solvent from the coagulating solution at a high recovery rate because the copolymer contained in the structure of the membrane is substantially not eluted into water contacted during the film formation process and the washing step.
A polysulfone membrane for purifying blood comprising a polysulfone and a graft copolymer consisting of (A) a hydrophilic segment and (B) a hydrophobic segment, the monomer unit ratio (A/B) of (A) to (B) being from 0.5 to 5 and the total of (A) and (B) being from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, wherein (B) is not polysulfone, and wherein (A) the hydrophilic segment and (B) the hydrophobic segment form the graft copolymer.
A polysulfone membrane for purifying blood comprising a polysulfone and a graft copolymer and/or block copolymer consisting of (A) a hydrophilic segment and (B) a hydrophobic segment, the monomer unit ratio (A/B) of (A) to (B) being from 0.5 to 5 and the total of (A) and (B) being from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, wherein (B) is not polysulfone, and wherein (B) the hydrophobic segment is a polystyrene segment.
A polysulfone membrane for purifying blood comprising a polysulfone and a graft copolymer and/or block copolymer consisting of (A) a hydrophilic segment and (B) a hydrophobic segment, the monomer unit ratio (A/B) of (A) to (B) being from 0.5 to 5 and wherein the total of the hydrophilic segment (A) and the hydrophobic segment (B) is from 6 to 20 parts by weight per 100 parts by weight of polysulfone, wherein (B) is not polysulfone.
A process for producing a polysulfone membrane for purifying blood, comprising dissolving polysulfonc and a graft copolymer comprising (A) a hydrophilic segment and (B) a hydrophobic segment in a total amount of from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, with the monomer unit ratio (A/B) between the segments (A) and (B) being from 0.5 to 5, in a predetermined solvent to have a polysulfone concentration of from 12 to 25 wt % based on the dope prepared, forming the film formation dope into a plane membrane or a hollow fiber, contacting the plane membrane or hollow fiber formed with a predetermined coagulating solution, removing the solvent and washing the residue;
A polysulfone membrane for purifying blood comprising a polysulfone and a graft copolymer and/or block copolymer consisting of (A) a hydrophilic segment and (B) a hydrophobic segment, the monomer unit ratio (A/B) of (A) to (B) being from 0.5 to 5 and the total of (A) and (B) being from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, wherein (B) is not a polysulfone, and wherein the monomer unit ratio (U=B'/A') between the hydrophobic segment (B') and the hydrophilic segment (A') present on the surface of the membrane is smaller than the monomer unit ratio (V=B/A) between the hydrophobic segment (B) and the hydrophilic segment (A) present in the entire membrane.
A process for producing a polysulfone membrane for purifying blood comprising dissolving polysulfone and a graft copolymer and/or block copolymer comprising (A) a hydrophilic segment and (B) a hydrophobic segment in a total amount of from 0.5 to 30 parts by weight per 100 parts by weight of polysulfone, with the monomer unit ratio (A/B) between the segments (A) and (B) being from 0.5 to 5, in a predetermined solvent to have a polysulfone at a concentration of from 12 to 25 wt % based on the dope prepared, forming the film formation dope into a plane membrane or a hollow fiber, contacting the plane membrane or hollow fiber formed with a predetermined coagulating solution, removing the solvent and washing the residue;
Dependencies are inferred from the claim text.