Ion exchange resins

An ion exchange resin having improved physical strength obtained by attaching a functional group selected from the class consisting of sulfonamide, trialkylamino, tetraalkyl ammonium, carboxyl, carboxylate, sulfonic, sulfonate, hydroxyalkyl ammonium, iminodiacetate, amine oxide, and phosphonate to the crosslinked copolymer prepared by the process of preparing hard, crosslinked discrete copolymer beads by the free radical polymerization in an aqueous dispersion of a monomer mixture comprosed of a major proportion of (a) monovinyl monomer and a minor proportion of (b) crosslinking monomer having at least two active vinyl groups, wherein the improvement comprises conducting the polymerization reaction at a temperature within the range of about 30.degree. to 95.degree. C. with a modifier in admixture with the aforesaid monomer mixture, the modifier being present in a concentration of from about 0.01 to about 10 millimoles per mole of monomers, in the monomer mixture (a) and (b), said modifier being an organic compound containing acetylenic or allylic unsaturation, said organic compound being capable of moderating rate of polymerization, and wherein, when the modifier contains allylic unsaturation, is selected from the group consisting of terpinolene, bicycloheptadiene, dimethyloctatriene, dimer of methyl cyclopentadiene, terpenes, 2-methyl styrene, .alpha.-methyl styrene dimer, limonene, cyclohexadiene, methyl cyclohexadiene, camphene, geraniol, farnesol, 2-norbornene, cyclododecatriene, cyclpooctadiene, cyclododecene, allyl benzene and 4-vinyl-1-cyclohexene