Polyether-polycarbonates for dialysis membranes

Claim 2

A process for the preparation of segmented aliphatic aromatic polyether-polycarbonates having Mw (weight-average) of 50,000 to 350,000 and containing about 95% by weight to about 65% by weight of 2,2-bis-(4-hydroxyphenyl)-propane carbonate structural units of the formula I ##STR5## and about 5% by weight to about 35% by weight of polyether-polycarbonate structural units of the formula II ##STR6## wherein O-polyether-O- is an aliphatic polyether diolate radical having an M n of 600 to 20,000 by the phase boundary process in a mixture of organic solvent, and aqueous alkaline phase at temperatures of 0° C. to 35° C. from corresponding quantities of aliphatic polyether diols having M n of 600 to 20,000, bisphenol A and phosgene, characterized in that (a) phosgene is used in a molar excess, based on the mols of organic dihydroxy compounds, (b) the aqueous phase is kept at a pH value of at least 13 and (c) polycondensation is carried out in a reactor by the addition of an amine catalyst, the polyether-polycarbonate being purified via the organic phase, isolated and dried.

Claim 3

A process for the production of a polyether-polycarbonate membrane of a thickness of between about 10 and 50 μm comprising (1) preparing a segmented aliphatic aromatic polyether-polycarbonate having a weight average molecular weight (M w ) of between about 50,000 and 350,000 and containing between about 95 and 65 weight percent of 2,2-bis-(4-hydroxyphenyl)-propane carbonate structural units of the formula I: ##STR7## and between about 5 and 35 weight percent of polyether-polycarbonate structural units of the formula II ##STR8## wherein O-polyether-O- is an aliphatic polyether diolate radical having a number average molecular weight (M n ) of between about 600 and 20,000; by reacting 2,2-bis-(4-hydroxyphenyl)-propane and at least one aliphatic polyether diol by the phase boundary process; (a) in a mixture of an organic solvent for the final polyether-polycarbonate and an aqueous alkaline phase with which the organic solvent is immiscible; (b) at a temperature between about 0° and 35° C.; (c) with a molar excess of phosgene based on the mols of organic dihydroxy compounds, (d) while keeping the pH of the aqueous alkaline phase at a value of at least about 13; (e) following the initial reaction with polycondensation in the presence of an amine catalyst in the organic solvent; (f) purifying the organic solvent solution of the polyether-polycarbonate; and (g) isolating the polyether-polycarbonate from the solvent and drying it; and (2) dissolving the polyether-polycarbonate in at least one organic water miscible solvent to a concentration between about 1 and 20 weight percent, based on the weight of the solution; (3) filtering this solution; (4) drawing a wet film of between about 150 and 240 μm onto a smooth surface; (5) evaporating off a portion of this water miscible solvent; and (6) hydrating the film several times with demineralized water.

Claim 4

A process for the production of a polyether-polycarbonate membrane of a thickness of between about 10 and 50 μm comprising (1) preparing a segmented aliphatic aromatic polyether-polycarbonate having a weight average molecular weight (M w ) of between about 50,000 and 350,000 and containing between about 95 and 65 weight percent of 2,2-bis-(4-hydroxyphenyl)-propane carbonate structural units of the formula I: ##STR7## and between about 5 and 35 weight percent of polyether-polycarbonate structural units of the formula II ##STR8## wherein O-polyether-O- is an aliphatic polyether diolate radical having a number average molecular weight (M n ) of between about 600 and 20,000; by reacting 2,2-bis-(4-hydroxyphenyl)-propane and at least one aliphatic polyether diol by the phase boundary process; (a) in a mixture of an organic solvent for the final polyether-polycarbonate and an aqueous alkaline phase with which the organic solvent is immiscible; (b) at a temperature between about 0° and 35° C.; (c) with a molar excess of phosgene based on the mols of organic dihydroxy compounds, (d) while keeping the pH of the aqueous alkaline phase at a value of at least about 13; (e) following the initial reaction with polycondensation in the presence of an amine catalyst in the organic solvent; (f) purifying the organic solvent solution of the polyether-polycarbonate; and (g) isolating the polyether-polycarbonate from the solvent and drying it; and (2) dissolving the polyether-polycarbonate in at least one organic water miscible solvent to a concentration between about 1 and 20 weight percent, based on the weight of the solution; (3) filtering this solution; (4) drawing a wet film of between about 150 and 240 μm onto a smooth surface; (5) evaporating off a portion of this water miscible solvent; and (6) hydrating the film several times with demineralized water.

Claim 5

Process according to claim 1 or 2, characterised in that (d) following polycondensation, but prior to the isolation of the polyether-polycarbonate a phenolic stabiliser is added in quantities of 10 to 1,000 ppm, based on the weight of the polyether-polycarbonate.

Claim 6

The process of claim 1 wherein said polyether carbonate further contains aryl carbonate structural units of the formula II ##STR9## wherein Ar is a carbocyclic, aromatic radical, said units being the derivatives of monophenolic chain stoppers which are introduced in said mixture.

Claim 7

The process of claim 2 wherein said phase boundary process further comprises adding a monohydroxy aromatic compound.

Claim 8

The process of claim 1 wherein said aqueous phase is kept at a pH value of 13 to 14.

Claim 9

The process of claim 1 wherein said aqueous phase is kept at a pH value of 14.