Patent ID: 6951911

Claim:
A cross-linked polymer (A), which comprises 1 or 2 or more vinyl series monomers (a) selected from the group consisting of a water-soluble vinyl series monomer and a monomer which becomes water-soluble by hydrolysis, and a cross-linking agent (b) as an essential component components, wherein said cross-linked polymer satisfies the following requirements 1 to 3: ( X )≧33 g/g, 1 ( Y )≧25 g/g, 2 ( y )≧−0.54( X )+42 3 wherein, (X) is a water retaining amount for a physiological saline after 1 hour absorption, and (Y) is an absorbing amount under 60 g/cm 2 load for a physiological saline after 1 hour; wherein said vinyl series monomer (a) is a water-soluble vinyl series monomer selected from (a1) having at least one functional group selected from the group consisting of carboxylic acid (carboxylate) group, sulfonic acid (sulfonate) group, sulfuric acid (sulfate) group, phosphoric acid (phosphate) group, hydroxy group, amido group, and quaternary ammonium salt group, a vinyl series monomer (a2) which becomes water soluble by hydrolysis, and which has at least one functional group selected from the group consisting of acid anhydride group, lower alkyl ester group, and nitrile group, or a combination of them.