Patent ID: 7022744

Claim:
An ion exchanger obtained by: subjecting the surface of porous organic polymer particles (A) to hydrophilic treatment, wherein said hydrophilic treatment is carried out by: allowing the porous organic polymer particles (A) to undergo an addition reaction with a compound (B) having a cyclic ether group, a hydrophilic group or both of them and a polymerizable unsaturated double bond and then to undergo copolymerization with a polymerizable vinyl monomer (C) having a cyclic ether group, a hydrophilic group or both of them, thus forming particles (D) having a hydrophilic surface; and introducing an amount of an ion exchange group into hydrophilic-surface porous organic polymer particles (D) to form an ion exchanger, which has an ion exchange capacity of 0.15 milliequivalent or less per 1 g of dry ion exchanger; wherein the introduced amount of the compound (B) is from 0.1 to 45% by weight based on the porous organic polymer particles (A), and wherein the copolymerized amount of the compound (C) is from 5 to 60% by weight based on the addition product obtained by allowing the porous organic polymer particles (A) to carry out the addition reaction with the compound (B).