| abstract |
Wet strength resins for paper are prepared by a process comprising the following steps in sequence: (1) reacting a polyamidoamine with an epihalohydrin until the amount of unreacted epihalohydrin present is less than about 10% by weight of the amount of epihalohydrin charged, (2) adding a water-soluble, nonpolymeric amine in an amount of about 0.1 to about 50 mole %, based on the amine in the polyamidoamine, and (3) heating to effect crosslinking. An optional amine additive reaction step can be included after step (2). A nonhalogen acid such as sulfuric acid can be added toward the end of the crosslinking step to decrease the total organic halogen content and increase the wet strengthening effectiveness. |