Polycarbonate-polyether-copolymer membrane
First Claim
1. An isotropic polycarbonate-polyether block copolymer membrane useful for hemodialysis, containing less than 0.5 weight percent impurities consisting essentially of(1) about 5 to 35 weight percent of repeating polyethylene-ether-carbonate units, the polyethylene oxide blocks of said copolymer having a molecular weight of from 1000 to 20,000, and(2) about 95 to 65 weight percent of repeating bisphenol A - carbonate units wherein the intrinsic viscosity of said copolymer ranges from about 180 to 300 ml/g as measured in chloroform at 25°
- C., andthe ultrafiltration rate of said membrane amounts to about 4 to 200 ml/h.m2 mmHg, said membrane being prepared by a wet extrusion process.
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Abstract
A method is provided for producing a membrane from polycarbonate-polyether-blockcopolymers with about 5 to 35 weight percent of repeating alkyleneethercarbonate units and about 95 to 65 weight percent of repeating bisphenol A-carbonate units, wherein the polyethyleneoxide blocks have a molecular weight from about 1,000 to 20,000, wherein the intrinsic viscosity of the copolymer is from about 180 to 300 ml/g as measured in chloroform at 25° C. and wherein the ultrafiltration rate is from about 4 to 200 ml/h.m2.mm Hg. In a first dissolving step a polycarbonate-polyether-copolymer is homogeneously mixed with a solvent at a temperature from about 80° to 120° C. and in a second dissolving step the temperature is brought to about 140° to 180° C. to produce a true solution. The filtered solution is cooled to from about 20° to 50° C. and is then extruded through a nozzle into a bath comprising a nonsolvent for the polymer for precipitating the polymer. The precipitated polymer is then washed and dried. The resulting membranes improve the processes of hemodialyzing and of homofiltration.
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Citations
12 Claims
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1. An isotropic polycarbonate-polyether block copolymer membrane useful for hemodialysis, containing less than 0.5 weight percent impurities consisting essentially of
(1) about 5 to 35 weight percent of repeating polyethylene-ether-carbonate units, the polyethylene oxide blocks of said copolymer having a molecular weight of from 1000 to 20,000, and (2) about 95 to 65 weight percent of repeating bisphenol A - carbonate units wherein the intrinsic viscosity of said copolymer ranges from about 180 to 300 ml/g as measured in chloroform at 25° - C., and
the ultrafiltration rate of said membrane amounts to about 4 to 200 ml/h.m2 mmHg, said membrane being prepared by a wet extrusion process. - View Dependent Claims (2, 3, 4, 5, 6)
- C., and
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7. An isotropic polycarbonate-polyether block copolymer membrane useful for hemodialysis, containing less than 0.5 weight percent impurities consisting essentially of
(1) about 5 to 35 weight percent of repeating polyethylene-ether-carbonate units, the polyethylene oxide blocks of said copolymer having a molecular weight of from 1000 to 20,000, and (2) about 95 to 65 weight percent of repeating bisphenol A - carbonate units wherein the intrinsic viscosity of said copolymer ranges from about 180 to 300 ml/g as measured in chloroform at 25° - C., and
The ultrafiltration rate of said membrane amounts to about 4 to 200 ml/h.m2 mmHg, said membrane being prepared by a wet extrusion process comprising the following steps; (a) dissolving said polycarbonate - polyether block copolymer in a solvent therefor at a temperature of from about 80°
-120°
C.,(b) increasing the temperature of said solution to about 140°
-180°
C.,(c) filtering said solution, (d) cooling said filtered solution to about 20°
-50°
C.,(e) extruding said solution through a nozzle into a bath containing a non-solvent for the copolymer for precipitating the polymer, and (f) drying the extruded precipitated polymer in the presence of measures for preventing longitudinal and cross-sectional shrinkage. - View Dependent Claims (8, 9, 10, 11, 12)
- C., and
Specification