Patent ID: 7932349

Claim:
A process for preparing polyamine-epihalohydrin resins having reduced levels of residuals comprising: (a) charging a membrane separation apparatus with an aqueous composition comprising at least one polyamine-epihalohydrin resin; and (b) separating said aqueous composition into a permeate and a retentate by passing said aqueous composition through the membrane of said membrane separation apparatus, wherein said retentate comprises an aqueous composition comprising at least one polyamine-epihalohydrin resin having lower levels of residuals on an equal active component basis than the aqueous composition of (a), and wherein said membrane is a polyamide nanofiltration membrane having a nominal cut off range of 150 Daltons to 1000 Daltons thereby providing said permeate with residuals removed from the aqueous composition of (a) and less than 5% by weight of the active component of said at least one polyamine-epihalohydrin resin.