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.
99 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