Abstract: A highly reactive, water-absorptive resin is prepared by (1) impregnating a highly water-absorptive resin having carboxyl or carboxylate groups and a water content of 50 percent by weight or lower with a hydrophilic polymer or monomer having a reactive group and (2) polymerizing said monomer or crosslinking said polymer with a crosslinking agent.

Abstract: An absorbent article comprises a base material of fibers a part or all of which fibers are hydrophobic and a water-absorbent polymer a part or all of which is in the form of substantially spherical particles and has been bonded to said fibers to surround them. Fixation of the polymer is secured. Softness of the base material is maintained.

Abstract: A polymer in the form of particles is water-insoluble and water-sellable, containing carboxyl or carboxylate groups. It has a physiological saline absorption quantity of 40 to 90 grams per one gram of the polymer, a physiological saline absorption rate of at least 8 ml per 0.3 gram of the polymer, a gel strength of 33 to 200 g/cm2 when it has been swollen to saturation with ion-exchange water. It is useful as an absorbent in a sanitary article.

Abstract: A highly water absorbent polymer having high resistance to salt solution is prepared by crosslinking a hyrophilic polymer or copolymer having carboxyl and/or carboxylate groups and water content of 10 to 40 wt. % with a crosslinking agent having at least two functional groups capable of reaction with said carboxyl and carboxylate group. An improved hydrophilic polymer is produced by polymerizing a monomer with a persulfate and a hydroperoxide as combined initiators. Another improved hydrophilic polymer is prepared by polymerizing a monomer with a persulfate and adding a hydroperoxide to the resulting polymer.