Permselective membranes and methods for their production
AssigneeToray Industries, Inc.
InventorsHidetoshi Kozawa, Ichiro Itagaki, Kenji Nishikawa, Kazumi Tanaka
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Abstract
Membrane materials for removing uremic toxins from a hydrophobic polymer such as polysulfone and two polyvinyl pyrrolidones, hydrophilic polymers of different molecular weights, that is 10-50 wt. % of a low molecular weight component (molecular weight<100,000) and 90-50 wt. % of a high molecular weight component (molecular weight≧100,000). The membranes are permselective useful in dialysis. The membrane material may have an overall mass transfer coefficient (K0), for a Strokes' radius of at least 30 Å (as determined by a diffusion test during dextran), of ≧0.0025 cm/min and a permeability to albumin of ≦4%.
Claims18
A membrane material for removing uremic toxins from the blood of patients, the membrane material comprising a polysulfone and a polyvinyl pyrrolidone wherein the polyvinyl pyrrolidone is present in the membrane material in an amount of 3 to 15% by weight of the polysulfone and the polyvinyl pyrrolidone, and the polyvinyl pyrrolidone consists of 10-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a low molecular weight component having a molecular weight, as measured by gel permeation chromatography, less than 100,000 and 90-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a high molecular weight component having a molecular weight, as measured by gel permeation chromatography, of 100,000 or more wherein a membrane made of the membrane material has an overall mass transfer coefficient (K0), for a Stoke's radius of at least 30 Å, as determined by dextran diffusion, of 0.0025 cm/min or more and a permeability to albumin of 4% or less.
A membrane material comprising a polysulfone and polyvinyl pyrrolidone wherein the polyvinyl pyrrolidone is present in the membrane material in an amount of 3 to 15% by weight of the polysulfone and the polyvinyl pyrrolidone, and the polyvinyl pyrrolidone consists of 10-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a low molecular weight component having a molecular weight, as measured by gel permeation chromatography, less than 100,000 and 90-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a high molecular weight component having a molecular weight, as measured by gel permeation chromatography, of 100,000 or more, which membrane material is partially crosslinked wherein a membrane made of the membrane material has an overall mass transfer coefficient (K0), for a Stoke's radius of a least 30 Å, as determined by dextran diffusion, of 0.0025 cm/min or more and a permeability to albumin of 4% or less.
A method of producing a polymeric membrane comprising the steps of:
- (a) forming a solution comprising a polysulfone, a polyvinyl pyrrolidone and a solvent, the polyvinyl pyrrolidone prepared by mixing at least two polyvinyl pyrrolidones having different respective molecular weights, a low molecular weight polyvinyl pyrrolidone having a weight average molecular weight, measured by gel permeation chromatography, of less than 100,000 and a high molecular weight polyvinyl pyrrolidone having a molecular weight of at least 100,000, the solvent being capable of dissolving both of the polysulfone and the polyvinyl pyrrolidone, wherein the solution contains from 1.8-20 wt. %, base don the total weight of the solution, of said high molecular weight polyvinyl pyrrolidone, and wherein the weight ratio of low to high molecular weight polyvinyl pyrrolidone in the solution formed in step (a) is between about 7:2 to about 2:7,
- (b) forming said solution into a membrane, and
- (c) removing the solvent from the membrane to obtain the polymeric membrane.
A membrane material for removing uremic toxins from the blood of patients, the membrane material comprising a polysulfone and a polyvinyl pyrrolidone wherein the polyvinyl pyrrolidone is present in the membrane material in an amount of 3 to 15% by weight of the total weight of the polysulfone and the polyvinyl pyrrolidone and the polyvinyl pyrrolidone consists of 10-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a low molecular weight component having a molecular weight, as measured by gel permeation chromatography, less than 100,000 and 90-50 wt. %, based on the total weight of polyvinyl pyrrolidone, of a high molecular weight component having a molecular weight, as measured by gel permeation chromatography, of 100,000 or more wherein a membrane made of the membrane material has an overall mass transfer coefficient (K0), for a Stoke's radius of a least 30 Å, as determined by dextran diffusion, of 0.0025 cm/min or more and a permeability to albumin of 4% or less.
Dependencies are inferred from the claim text.