To provide a granular water-absorbent resin which has a large granular size and a high agglomeration strength and a process for producing the same.
This granular water-absorbent resin has an average granular size of 200-10,000 μm and is formed by agglomerating bead-like water-absorbent resin primary particles having two or more frequency distributions and having a ratio of the max. median particle size to a median particle size lower than the max. median particle size of (3,000/1)-(1.5/1). The bead-like water-absorbent resin pimary paticles, having two or more frequency distributions and used for preparing the granular water- absorbent resin, are obtd. by subjecting a water-soluble ethylenically unsatd. monomer to reversed phase suspension polymn. of a water-in-oil type by using a water-soluble free-radical polymn. initiator in the presence of a dispersant in a hydrophobic org. solvent, optionally in the presence of a crosslinker, to form water-contg. bead-like water-absorbent resin primary particles, then adding a water-soluble ethylenically unsatd. monomer to a slurry of the polymn. system contg. the water-contg. bead-like water-absorbent resin to case the primary particles to absorb the water soln., conducting the additional suspension polymn., and repeating the above-mentioned process at least twice.
YOSHIHARA MICHITOKU
ITO KIICHI
