US 12,226,738 B2
Combination of pyrrolidone based solvents for the production of porous membranes
Jan Schwellenbach, Göttingen (DE); Catharina Warnke, Göttingen (DE); and Sandra Otto, Göttingen (DE)
Assigned to Sartorius Stedim Biotech GMBH, Gottingen (DE)
Appl. No. 17/607,353
Filed by Sartorius Stedim Biotech GmbH, Göttingen (DE)
PCT Filed Jun. 25, 2020, PCT No. PCT/EP2020/067862
§ 371(c)(1), (2) Date Oct. 28, 2021,
PCT Pub. No. WO2020/260473, PCT Pub. Date Dec. 30, 2020.
Claims priority of application No. 19182866 (EP), filed on Jun. 27, 2019.
Prior Publication US 2022/0203306 A1, Jun. 30, 2022
Int. Cl. B01D 67/00 (2006.01); B01D 71/68 (2006.01)
CPC B01D 67/00111 (2022.08) [B01D 71/68 (2013.01); B01D 2325/021 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for producing a porous membrane, the method comprising the following steps (a) to (d):
(a) providing a casting solution, wherein the casting solution comprises polyethersulfone as a membrane-forming polymer dissolved in a solvent system comprising 2-pyrrolidone and N-n-butyl-2-pyrrolidone but not comprising dimethyl sulfoxide, wherein the casting solution further comprises at least one additive selected from the group consisting of polyvinylpyrrolidone, polyvinylpyrrolidone-co-polyvinylacetate, and polyethylene glycol;
(b) forming a polymer film from the casting solution provided in step (a);
(c) contacting the polymer film formed in step (b) with a liquid precipitation bath, with a gaseous phase comprising a precipitation-inducing agent or with a combination thereof to induce membrane formation, thereby obtaining a porous membrane; and
(d) drying the porous membrane obtained in step (c),
wherein the content ratio of 2-pyrrolidone to N-n-butyl-2-pyrrolidone in the solvent system is in the range of from 80%:20% to 50%:50% based on mass %.