Improvement in production of superabsorbent polyacrylate

PURPOSE: To economically obtain a powder superabsorbent of a large particle size with narrow distribution of particle sizes and excellent water absorbing property by using two kinds of acrylic acid monomers having different neutrali zation degrees in the respective stages when acrylic monomers are subjected to inverse suspension polymn. in two stages. CONSTITUTION: First, an aq. phase containing acrylic acid monomers which are neutralized to a higher degree than the polyacrylic acid of the final product is introduced into a solvent phase to polymerize the monomers in an inverse suspension liquid. Then the produced polymer gel is made to absorb an aq. phase containing acrylic acid monomers neutralized to a lower degree than the polyacrylic acid of the final product to polymerize. Finally, the produced polymer is separated, and usually dried to obtain the objective product comprising partially neutralized polyacrylic acid for water and a water-based liquid. It is preferable to use monomers having 90 to 100% neutralization degree in the first stage and monomers having 65 to 50% neutralization degree in the second stage and to obtain the final polyacrylic acid having 75% neutralization degree. COPYRIGHT: (C)1994,JPO