Patent ID: 8101710

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 residuals; (b) separating said aqueous composition into a permeate and a retentate by passing said aqueous composition through a membrane of said membrane separation apparatus, wherein said membrane is a nanofiltration membrane having a nominal cut off range of 150 Daltons to 1000 Daltons, and wherein said retentate comprises the at least one polyamine-epihalohydrin resin, and a lower level of residuals on an equal active component basis than the aqueous composition of (a), and wherein said permeate comprises residuals removed from the aqueous composition of (a); and (c) treating the retentate with at least one basic agent under conditions to reduce and/or remove 3-chloropropanediol (CPD)-forming species, wherein the base treated retentate produces less than about 250 ppm dry basis of CPD when stored at pH 1 for 24 hours at 50° C.