Asymmetrical microporous hollow fiber for hemodialysis
First Claim
1. An asymmetric microporous wettable hollow fiber, consisting essentially of an inner barrier layer and an outer foam-like supporting structure said fiber comprising a hydrophobic first organic polymer in an amount equal to 90 to 99% by weight and 10 to 1% by weight of polyvinyl pyrrolidone which is produced by the following steps:
- (a) wet spinning a polymer solution made up of a solvent, of 12 to 20% by weight of the first said polymer and of 2 to 10% by weight of the polyvinyl pyrrolidone, said solution having a viscosity of 500 to 3,000 cps, through a ring duct of a spinnerette having an external ring duct and an internal hollow core,(b) simultaneously passing through said hollow internal core a precipitant solution comprising an aprotic solvent in conjunction with at least 25% by weight of a nonsolvent which acts in an outward direction on the polymer solution after issuing from the spinneret(c) casting into an aqueous washing bath, said spinnerette and the upper surface of said washing bath being separated by an air gap, said air gap being so provided that full precipitation of components will have occurred before the precipitated polymer solution enters said washing bath thereby,(d) dissolving out and washing away a substantial portion of the polyvinyl pyrrolidone and of the said solvent, to form a fibre having a high clearance rate according to DIN 58352, of 200-290 ml/min for urea and 200-250 ml/min for creatinine and phosphate, at a blood flow rate of 300 ml/min., for fibres having 1.25 m2 of active surface.
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Abstract
An asymmetric microporous hollow fiber for hemodialysis is made up of 90 to 99% by weight of a first hydrophobic polymer and 10 to 1% by weight of a second hydrophilic polymer. The fiber has a water adsorbing capacity of 3 to 10% and is produced by extruding a solution containing 12 to 20% by weight of the first polymer and 2 to 10% by weight of the second polymer, the rest being a solvent to give a continuous hollow structure with a wall, causing a precipitation liquor to act on said structure in an outward direction through the wall thereof with the full precipitation thereof and the concurrent dissolution and washing out of a part of said first polymer from said extruded structure and then washing out the dissolved out part of the pore-forming substance and the other organic components. Thereafter the fiber so produced is fixed in a washing bath.
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Citations
24 Claims
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1. An asymmetric microporous wettable hollow fiber, consisting essentially of an inner barrier layer and an outer foam-like supporting structure said fiber comprising a hydrophobic first organic polymer in an amount equal to 90 to 99% by weight and 10 to 1% by weight of polyvinyl pyrrolidone which is produced by the following steps:
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(a) wet spinning a polymer solution made up of a solvent, of 12 to 20% by weight of the first said polymer and of 2 to 10% by weight of the polyvinyl pyrrolidone, said solution having a viscosity of 500 to 3,000 cps, through a ring duct of a spinnerette having an external ring duct and an internal hollow core, (b) simultaneously passing through said hollow internal core a precipitant solution comprising an aprotic solvent in conjunction with at least 25% by weight of a nonsolvent which acts in an outward direction on the polymer solution after issuing from the spinneret (c) casting into an aqueous washing bath, said spinnerette and the upper surface of said washing bath being separated by an air gap, said air gap being so provided that full precipitation of components will have occurred before the precipitated polymer solution enters said washing bath thereby, (d) dissolving out and washing away a substantial portion of the polyvinyl pyrrolidone and of the said solvent, to form a fibre having a high clearance rate according to DIN 58352, of 200-290 ml/min for urea and 200-250 ml/min for creatinine and phosphate, at a blood flow rate of 300 ml/min., for fibres having 1.25 m2 of active surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An asymmetric microporous wettable hollow fiber, consisting essentially of an inner barrier layer and an outer foam-like supporting structure said fiber comprising a hydrophobic first organic polymer in an amount equal to 90 to 99% by weight and 10 to 1% by weight of polyvinyl pyrrolidone said fibre having the following characteristics:
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(a) a high rate of water permeability of about 30-600 ml/h per sq. meter per mmHg, (b) a high clearance rate according to DIN 58352, of 200-290 ml/min for urea, 200-250 ml/min for Vitamin B12 and 50-120 ml/min for inulin, at a blood flow rate of 200-250 ml/min creatinine and phosphate, 300 ml/min., for fibres having 1.25 m2 of active surface and (c) high sieving coefficients of 1.0 for Vitamin B12, about 0.99 for inulin, 0.5-0.6 for myoglobin and under 0.005 for human albumin. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification