Super absorbent polymer and a preparation method thereof

A super absorbent polymer (SAP), having the SPAN value of 1.2 or less, represented by the following Mathematical Formula 1, and

• satisfying the absorbing rate under load represented by the following Mathematical Formula 2:
• SPAN=[D(90%)−D(10%)]/D(50%)≦1.2 [Mathematical Formula 1]
• in Mathematical Formula 1,
• D(90%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 90%,
• D(10%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 10%, and
• D(50%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 50%,
• 1.0>ARUL=AUP(10 min)/AUP(60 min)>0.70 [Mathematical Formula 2]
• in Mathematical Formula 2,
• ARUL is the absorbing rate under load, AUP (10 min) is the absorbency under pressure after 10 mins represented by the following Mathematical Formula 3, and AUP (60 min) absorbency under pressure after 60 mins represented by the following Mathematical Formula 3,
• AUP(g/g)=[Wb(g)−Wa(g)]/weight of absorbent polymer(g) [Mathematical Formula 3]
• in Mathematical Formula 3,
• Wa (g) is the sum of the weight of the absorbent polymer and the weight of the device capable of providing load to the absorbent polymer, and
• Wb (g) is the sum of the weight of the absorbent polymer in which moisture is absorbed under load (0.7 psi) for 1 hr and the weight of the device capable of providing load to the absorbent polymer.