POLYACRYLIC ACID (SALT), WATER-ABSORBING RESIN AND ITS PRODUCTION, AND SANITARY MATERIAL

摘要

PROBLEM TO BE SOLVED: To obtain the subject polymer having excellent physical properties and giving, for example, a water-absorbing resin having a high water-absorbing rate and a reduced water-soluble component content by improving the dissociation degree of carboxyl groups as dissociating groups to increase the effective electric charge of the polyacrylic acid (salt). SOLUTION: This polyacrylic acid (salt) has a pKa value of <=6.2 and an (n) value of 1.0-2.0 in Henderson-Hasselbach' equation: pH=pKa+n log[α/(1-α)]. It is preferable that 60-80 mol.% of the carboxyl groups of the polyacrylic acid (salt) is neutralized. The polyacrylic acid (salt) is preferably obtained by subjecting an aqueous monomer solution containing a monovinyl ether and an acrylic acid salt to a copolymerization reaction using a radical polymerization initiator. The copolymerization of the monovinyl ether is preferably carried out by an alternating copolymerization method. The monovinyl ether is preferably ethylene glycol monovinyl ether. The acrylic acid salt is preferably a 100% neutralized acrylate salt.