Procedure for the polymer fractionation with broad molecular weight distribution, containing amino-soluble or water-dispersing groups.

Process for the fractionation of polymers containing amino, synthetic, soluble or water-dispersing groups by ultrafiltration, comprising the method the following steps: a) continuous driving of the polymer solution or dispersion to an ultrafiltration unit and mixing with retentate recycled from step d) and, optionally, with an aqueous medium essentially free of polymer, b) separation of the mixture in the ultrafiltration unit into a permeate and a retentate, c) discharge of the permeate from process, d) discharge of some of the retentate; recycling another part of the retentate to step a), e) driving the part discharged in step d) of the retentate to at least another ultrafiltration unit and treatment by a process with steps a) to d) .