Patent ID: 6599989
Filing Date: 2003-07-29
Classification: A61F,A61L,B01J,C08F,C08J,G01N

Abstract:
A water-absorbing agent prepared from an internally crosslinked water-absorbent resin that has been dried and then surface-crosslinked, with the water-absorbing agent:a) having an absorption capacity of 30 (g/g) or more under no load and a static deterioration absorption capacity (1) of 20 (g/g) or more under a load, wherein the static deterioration absorption capacity (1) under a load is an absorption capacity of the water-absorbing agent as determined by the following sequential steps of: i) swelling a water-absorbing agent to 15 (g/g) with a physiological sodium chloride solution containing L-ascorbic acid in a concentration of 0.005 weight %; ii) leaving the water-absorbing agent in such a swollen state for 6 hours; iii) allowing the swollen water-absorbing agent to absorb the physiological sodium chloride solution for another 1 hour in a state where a load of 50 g/cm2 is mounted on the swollen water-absorbing agent; and iv) measuring the weight of the resultant swollen gel; and b) comprising a water-absorbent resin that is internally crosslinked and surface crosslinked, wherein the water-absorbing resin is obtained by a process comprising the steps of: i) providing a monomer solution of which the main monomer component is acrylic acid and/or a salt, where the salt is a neutralized product of the acid, and carrying out a polymerization and internal crosslinking reaction with said monomer solution to obtain an internally crosslinked water-absorbent hydrogel; ii) drying the internally crosslinked water-absorbent hydrogel to obtain a dry internally crosslinked water-absorbent resin; and iii) carrying out a surface-crosslinking reaction with the dry internally crosslinked water-absorbent resin to obtain the water-absorbent resin that is internally crosslinked and surface crosslinked.