A process for producing monodisperse gel-type cation exchangers

The present invention relates to a method for producing monodisperse gel-type cation exchanger with an increased oxidation stability and high osmotic stability and purity which are obtained by DOLLAR A a) monodisperse microencapsulated monomer from a monomer mixture 1, comprising from 90.5 to 97.99 parts by weight % styrene, 2 to 7 wt .-% of divinylbenzene, and 0.01 to 2.5 wt .-% radical former in an aqueous suspension to sales polymerized from 76 to 100%, DOLLAR a b), a monomer 2 from 70.5 to 95 , 99 wt .-% styrene, 4 to 15 wt .-% of divinylbenzene, 0 to 12 wt .-% of a third comonomer and 0.01 to 2.5 wt .-% of one or more free-radical formers is added to form a copolymer wherein adding a partial amount of 50 to 100 wt .-% of the monomer mixture 2 under polymerizing conditions under which at least a radical of the monomer mixture 2 is active, and finally DOLLAR a c) the reaction product of Verfahrensschr itt b) functionalized by sulfonation, DOLLAR A the cation exchanger itself as well as uses thereof.