| 摘要 |
PURPOSE:To obtain the title resin having high water absorptivity and a high water absorption rate and such a particle diameter as not to require countermeasures against dusting, by polymerizing a specified aqueous monomer solution by slowly dropping it into a hydrocarbon solvent and dispersing it therein. CONSTITUTION:0.01-5.0wt%, based on monomer, water-soluble crosslinking agent having at least two polymerizable unsaturated groups or functional groups reactive with carboxyl groups and 0.01-5.0wt% water-soluble radical initiator are added to a 30-42wt%-concentration aqueous monomer solution containing an ethylenically unsaturated monomer such as a vinyl monomer having a carboxyl group or a carboxylate group (e.g., acrylic acid). 3-30wt% surfactant of an HLB of 2-3 is added to 4pts.wt., per pt.wt. said monomer, at least one solvent selected from among an aliphatic hydrocarbon, an alicyclic hydrocarbon and a mixture thereof, and this mixture is heated to a polymerization temperature of 30-100 deg.C. Said aqueous monomer solution is added dropwise little by little to the above mixture so that the rise of the polymerization temperature may be controlled to within 20 deg.C, dispersed by agitation and polymerized slowly to obtain the title resin of an average particle diameter of 70-200mu.
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