Water absorbent agent
Provided is a water-absorbing agent which maintains a certain degree of liquid permeability and water absorption speed while also reducing re-wet in a disposable diaper, without the use of costly raw materials or costly apparatuses. The water-absorbing agent of the present invention contains a polyacrylic acid salt-based water-absorbing resin as a main component and has physical properties falling within a specific range, the physical properties being saline flow conductivity (SFC), gap fluid retention property under pressure, and a proportion of particles having a particle diameter of not less than 150 μm and less than 710 μm.
1. A water-absorbing agent comprising:
a polyacrylic acid (salt)-based water-absorbing resin as a main component, said water-absorbing agent satisfying (A) to (C) below:
(A) a saline flow conductivity (SFC) is not less than 20×10 −7 ·cm 3 ·s·g −1 ;
(B) a gap fluid retention property under pressure is not less than 9 g/g; and
(C) a proportion of particles having a particle diameter of not less than 150 μm and less than 710 μm is not less than 90 weight %;
wherein, in (B), when a water-absorbing resin is swollen in a 0.69 weight % aqueous sodium chloride solution, said gap fluid retention property under pressure is a weight of the aqueous sodium chloride solution per gram of said water-absorbing agent, the sodium chloride solution being retained under a load of 2.07 kPa in gaps within said water-absorbing agent.
2. The water-absorbing agent according to claim 1 , further satisfying (D) below:
(D) a centrifuge retention capacity (CRC) is not less than 25 g/g.
3. The water-absorbing agent according to claim 1 , further satisfying (E) below:
(E) a fluid retention capacity under pressure (AAP) is not less than 20 g/g.
4. The water-absorbing agent according to claim 1 , further satisfying (F) below:
(F) a water absorption speed (FSR) is not less than 0.25 g/g/s.
5. The water-absorbing agent according to claim 1 , further satisfying (G) and/or (H) below:
(G) a weight average particle diameter (D50) is 300 μm to 450 μm; and
(H) a logarithmic standard deviation (GO of a particle size distribution is 0.25 to 0.45.
6. The water-absorbing agent according to claim 1 , further comprising, as a liquid permeability improving agent, at least one material selected from a group consisting of a polyvalent metal cation, a cationic polymer and inorganic fine particles.
7. The water-absorbing agent according to claim 1 , further comprising:
a surfactant and/or a dispersant.
8. The water-absorbing agent according to claim 1 , wherein said water-absorbing agent is used for an absorbent body included in an absorbent article.
9. An absorbent article comprising: a water-absorbing agent according to claim 1 .
10. The water-absorbing agent according to claim 1 , wherein the gap fluid retention property under pressure is not less than 10 g/g.