POLYACRYLIC ACID-BASED WATER-ABSORBING RESIN POWDER AND METHOD FOR PRODUCING THE SAME

摘要

A method for producing a polyacrylic water-absorbent resin powder includes the steps of: producing an acrylic monomer solution in which gas is dissolved and/or dispersed; polymerizing the monomer solution in the absence of a surface active agent or in the presence of not more than 300 ppm of a surface active agent; during or after polymerizing, fragmenting the resulting hydrated gel crosslinked polymer; and drying the fragmented hydrated gel crosslinked polymer, the gas being dissolved and/or dispersed in the monomer solution by (a) applying pressure to the acrylic monomer solution and the gas; (b) creating swirling flows of the acrylic monomer solution and the gas; or (c) introducing the gas with the acrylic monomer solution via fine holes. The production method efficiently produces a water-absorbent resin having an excellent water-absorption rate without deteriorating a liquid-absorbent property of a sanitary product or the like.

主权项

1. A polyacrylic water-absorbent resin powder production method comprising the steps of:
producing an acrylic monomer solution in which gas is dissolved and/or dispersed; polymerizing the acrylic monomer solution in the absence of a surface active agent or in the presence of not more than 300 ppm of a surface active agent; during or after the step of polymerizing, fragmenting a hydrated gel crosslinked polymer obtained by polymerizing the acrylic monomer solution; and drying by heat the hydrated gel crosslinked polymer thus fragmented, (1) the gas being dissolved and/or dispersed in the acrylic monomer solution by at least one of the methods (a) to (c):
(a) applying pressure to the acrylic monomer solution and the gas;(b) creating swirling flows of the acrylic monomer solution and the gas; and(c) introducing the gas with the acrylic monomer solution via fine holes, (2) the acrylic monomer solution having a kaolin turbidity of more than 0 but not more than 1000 [mg/L (degree)], or (3) the polyacrylic water-absorbent resin powder production method further comprising the step of defoaming to eliminate some of bubbles included in the acrylic monomer solution, the step of polymerizing the acrylic monomer solution including the bubbles being carried out after the step of defoaming.