Patent ID: 8211950

Claim:
A process for producing an amphoteric ion exchanger, comprising the steps of: a) reacting monomer droplets of a mixture of at least one monovinylaromatic compound, at least one polyvinylaromatic compound, an initiator or an initiator combination, thereby forming crosslinked polymer beads, b) amidomethylating the crosslinked polymer beads with phthalimide derivatives, thereby forming phthalimidomethylated polymer beads, c) reacting the phthalimidomethylated polymer beads with a substoichiometric amount of a saponification reagent, thereby forming a product mixture, wherein the substioichomitric amount of the molar ratio of the phthalimidomethylated polymer bead to said saponification reagent is less than 1: 2.0; and d) isolating the amphoteric ion exchanger from the product mixture.