Method for the production of a filtration membrane having a mean molecular weight cut-off of < 1000 g/mol

A process for preparing a filtration membrane having an average molecular cut-off less than 1000 g/mol, the process comprising:

• a) contacting at least one filtration membrane having an average molecular cut-off between 3,000 g/mol and 15,000 g/mol, and comprising at least one bonded textile fabric coated with at least one of:
• a polyether sulphone and a hydrophilicized polyether sulphone, with an aqueous medium having a water content of not less than 99%,
• b) contacting the filtration membrane from step a) with at least one polyethylene glycol in the presence of at least one different aliphatic, cyclic or non-cyclic, branched or unbranched, saturated or unsaturated, mono-, di- or trihydric alcohol, wherein the polyethylene glycol is used in an amount of 5 wt % to 50 wt %, based on the combined amount of polyethylene glycol and alcohol, and the sum total of polyethylene glycol and alcohol used in process step b) is greater than 95 wt %, based on the overall amount of the mixture used, and
• c) drying the filtration membrane from step b).