Water-absorbing agent and production process therefor, and sanitary material

A water-absorbing agent, which is a particulate water-absorbing agent of which the major proportion is comprised of a water-absorbent resin that is obtained by a process including the step of polymerizing an unsaturated monomer component and has a crosslinked structure,

• with the water-absorbing agent being characterized in that:
• the particulate water-absorbing agent includes particles having particle diameters of smaller than 850 μm but not smaller than 150 μm in a ratio of not less than 90 weight % of all particles of the particulate water-absorbing agent;
• and includes at least two members selected from the group consisting of:
• particles (A1) having particle diameters of smaller than 850 μm but not smaller than 600 μm;
• particles (A2) having particle diameters of smaller than 600 μm but not smaller than 500 μm;
• particles (A3) having particle diameters of smaller than 500 μm but not smaller than 300 μg/m;
• and particles (A4) having particle diameters of smaller than 300 μm but not smaller than 150 μm;
• and further satisfies the following properties:
• a 30 minutes' absorption capacity of not less than 31 g/g without load for a 0.90 weight % physiological saline (CRC);
• a 60 minutes' absorption capacity of not less than 24 g/g under a load of 4.83 kPa for a 0.90 weight % physiological saline (AAP);
• a saline flow conductivity of not less than 20 (unit:
• 10−7×cm3×s×g−1) for a 0.69 weight % physiological saline (SFC);
• and
• an SFC variation coefficient of 0 to 0.25, wherein the SFC variation coefficient is defined by the following equation (2):
• SFC variation coefficient=(standard deviation of SFCs of particles A1 to A4)/(average of SFCs of particles A1 to A4) (2).

A continuously produced water-absorbing agent, which is a particulate water-absorbing agent of which the major proportion is comprised of a water-absorbent resin that is obtained by a process including the step of polymerizing an unsaturated monomer component and has a crosslinked structure,

• with the water-absorbing agent being characterized in that:
• the particulate water-absorbing agent includes particles having particle diameters of smaller than 850 μm but not smaller than 150 μm in a ratio of not less than 90 weight % of all particles of the particulate water-absorbing agent;
• and includes at least two members selected from the group consisting of:
• particles (A1) having particle diameters of smaller than 850 μm but not smaller than 600 μm;
• particles (A2) having particle diameters of smaller than 600 μm but not smaller than 500 μm;
• particles (A3) having particle diameters of smaller than 500 μm but not smaller than 300 μm;
• and particles (A4) having particle diameters of smaller than 300 μm but not smaller than 150 μm;
• and further satisfies the following properties:
• a 30 minutes' absorption capacity of not less than 31 g/g without load for a 0.90 weight % physiological saline (CRC);
• a 60 minutes' absorption capacity of not less than 24 g/g under a load of 4.83 kPa for a 0.90 weight % physiological saline (AAP);
• a saline flow conductivity of not less than 20 (unit:
• 10−7×cm3×s×g−1) for a 0.69 weight % physiological saline (SFC);
• and
• an SFC standard deviation of not more than 5.0 in a continuous production system, wherein the SFC standard deviation in a continuous production system is defined by the following equation (4):
• SFC standard deviation in a continuous production system=standard deviation of SFC of each lot (4)
• where:
• the CRC, AAP, and SFC are on average of the lots;
• each lot has a weight of not less than 20 kg;
• and the number of the lots is not smaller than 10.

A water-absorbing agent, which is a particulate water-absorbing agent obtained by a process including the steps of:

• polymerizing a monomer including an acid-group-containing monomer (salt);
• and then post-neutralizing the resultant polymer;
• and then surface-crosslinking the resultant water-absorbent resin,
• with the water-absorbing agent being characterized in that the particulate water-absorbing agent or the water-absorbent resin has a neutralization index of not less than 15 and exhibits a 60 minutes' absorption capacity of not less than 20 g/g under a load of 4.83 kPa for a 0.90 weight % physiological saline (AAP) after the surface-cross-linking.