Abstract: An aqueouse composition of an acrylic polymer to which a water soluble peroxide radical initiator has been added, said initiator being adapted to decompose at a temperature of from about 40.degree. C. to about 180.degree. C. and act on the polymer to crosslink the same. Using the aqueous composition, a water absorbent crosslinked polymer and a water absorbent polymer-coated article can be produced through simplified processes. The water absorbent crosslinked polymer exhibits excellent water absorbing and swelling properties so that it can be advantageously utilized for the production of wet absorbent articles such as disposable diaper, sanitary napkin or the like. The water absorbent polymer-coated article is excellent in water absorption properties and can be used safely for the purposes as mentioned above.

Abstract: An aqueous composition of an acrylic polymer to which a water soluble peroxide radical initiator has been added, said initiator being adapted to decompose at a temperature of from about 40.degree. C. to about 180.degree. C. and act on the polymer to crosslink the same. Using the aqueous composition, a water absorbent crosslinked polymer and a water absorbent polymer-coated article can be produced through simplified processes. The water absorbent crosslinked polymer exhibits excellent water absorbing and swelling properties so that it can be advantageously utilized for the production of wet absorbent articles such as disposable diaper, sanitary napkin or the like. The water absorbent polymer-coated article is excellent in water absorption properties and can be used safely for the purposes as mentioned above.

Abstract: A process for improving a water absorbent polyacrylic acid polymer in which the polymer is contacted with an aqueous solution containing a water soluble peroxide radical initiator, followed by heating, thereby causing substantially only the surface portion of the polymer to undergo crosslinking with the radical initiator while leaving the remaining core portion of the polymer substantially intact. The improved water absorbent polyacrylic acid polymer is excellent in both water absorbency and water absorption rate, and the hydrogel resulting from absorption of water has a pleasant, non-sticky feel. The improved water absorbent polyacrylic acid polymer can be advantageously utilized to produce a desirable disposable diaper, sanitary napkin, surgical pad, surgical sheet, paper towel or the like.

Abstract: A water absorbent fibrous product comprising a fibrous cellulosic material impregnated with a water absorbent acrylic polymer and a fibrous material, which is produced by a method in which an aqueous solution of a monomeric component comprising acrylic acid and a radical initiator is diffused in a fibrous cellulosic material and heated, followed by blending with a fibrous material. The fibrous product exhibits a high water absorbency, and finds applications as high-quality disposable diapers, sanitary napkins, surgical pads, surgical sheets, paper towels or the like.

Abstract: A water absorbent crosslinked polymer having at least 70% by weight of acrylic acid monomeric units, 60 to 90% of the carboxyl groups of which are in the form of an alkali metal salt, produced by a method in which a mixture comprised of acrylic acid, 60 to 90% of the carboxyl groups of which are in the form of an alkali metal salt, and a fibrous cellulosic material is heated in the presence of a radical initiator. The polymerization temperature can be effectively controlled by smooth evaporation of water. The cross-linked polymer can absorb such a large amount of water as several hundred times the weight of the polymer in an excellent absorption rate, and finds applications as, for example, a disposable diaper and a sanitary napkin.