Patent ID: 7943705

Claim:
A process for preparing a polyamidoamine-epichlorohydrin resin comprising the steps of: (1) reacting a polycarboxylic acid or a polycarboxylic acid derivative with an excess of a polyamine to form a polyamidoamine; and (2) reacting the polyamidoamine of (1) with epichlorohydrin to form a polyamidoamine-epichlorohydrin resin; wherein the molar ratio of said polyamine to said polycarboxylic acid is in the range of from 1.02:1 to 1.48:1; and wherein the weight percent of epichlorohydrin to polyamidoamine in step (2) is from 3.85% to 47%, and the maximum weight ratio of epichlorohydrin to the solids of polyamidoamine used in step (2) is no greater than about the calculated result of the mathematical expression [0.308-(amine number/RSV)—9.18], wherein said amine number is expressed as the milliequivalents of amine per gram of polyamidoamine solids and said RSV is the reduced specific viscosity measured at 2% concentration in 1 M NH 4 Cl expressed in deciliters per gram.