Superabsorbent polymer having high absorption rate under load and preparation method thereof

A porous superabsorbent polymer comprising

• a crosslinked polymer resulting from polymerization and internal crosslinking of a monomer composition comprising acrylic acid-based monomers having acidic groups which are at least partially neutralized, a low-temperature foaming agent, and a high-temperature foaming agent, and
• a surface crosslinking layer formed on the surface of the crosslinked polymer,
• wherein the superabsorbent polymer has centrifuge retention capacity (CRC) as 29.5 g/g or more, absorbency under load (AUL) as 18 g/g or more, gel bed permeability (GBP) as 60 Darcy or more, and 5-min gel-AUL as 18.0 g/g or more,
• wherein a ratio (A:B) of a total pore area (A) of micropores having a diameter of 5 μm to 100 μm and a total pore area (B) of macropores having a diameter of 100 μm to 400 μm in the superabsorbent polymer is 3:7 to 9:1, and the micropores and the micropores have different diameters, and
• a weight ratio of the low-temperature foaming agent and the high-temperature foaming agent is 50:1 to 2:1.