MONODISPERSED WEAK ACIDIC CATION EXCHANGER

PROBLEM TO BE SOLVED: To provide a poly(meth)acrylic acid-based cation exchanger characterized by having a high mechanical stability and high osmosis stability of beads, low pressure loss of bead heads upon use, and low consumption of washing water upon the use of the cation exchanger. SOLUTION: The method for producing the poly(meth)acrylic acid-type cation exchanger comprises (a) preparing encapsulated bead-type monomer droplets continuously or preferably in a liquid phase while, if necessary, heating the phase at a temperature of 50°C or higher, (b) mixing the encapsulated bead-type monomer droplets with a (meth)acrylic monomer, a crosslinking agent, and a polymerization initiator and if necessary a mixture of porogen under, if necessary, polymerization conditions, followed by copolymerization if the mixture infiltrates into the encapsulated droplets and addition is carried out under polymerization conditions, (c) polymerizing the encapsulated droplets at a high temperature, and (d) hydrolyzing the thus obtained cross-linked (meth)acrylic bead polymer using acid or alkali, so as to prepare a poly(meth)acrylic acid-type cross-linked bead polymer. COPYRIGHT: (C)2008,JPO&INPIT