Super absorbent polymer
The present invention relates to a super absorbent polymer. The super absorbent polymer according to the present invention includes surface crosslinked polymer particles prepared by surface crosslinking particles of a base resin, wherein the base resin is polymerized from water-soluble ethylene-based unsaturated monomers, and a water-soluble component, in which the water-soluble component is present in an amount of 5% by weight or less based on the total weight of the super absorbent polymer, when measured after free swelling the super absorbent polymer in a 0.9% NaCl solution for 1 hour, and the super absorbent polymer has a permeability of 50 seconds or shorter. According to the present invention, provided is a super absorbent polymer having excellent liquid permeability even when swollen without a reduction in centrifuge retention capacity or absorbency under load while having improved permeability.
1. A super absorbent polymer, comprising:
surface crosslinked polymer particles prepared by surface crosslinking particles of a base resin, wherein the base resin is polymerized from a monomer composition including water-soluble ethylene-based unsaturated monomers; and a water-soluble component,
wherein the base resin is polymerized in the presence of an internal cross linking agent, which crosslinks polymers present in an interior of the polymer particles and the internal cross linking agent is present in an amount ranging from 0.1 to 0.5 wt % based on the monomer composition, and
wherein the water-soluble component is present in an amount of 5%by weight or less based on the total weight of the super absorbent polymer, when measured after free swelling the super absorbent polymer in a 0.9% NaCl solution for 1 hour, and
wherein the super absorbent polymer has a permeability calculated by the following Equation 1 of about 50 seconds or shorter:
Permeability (sec) = T S −T 0 [Equation 1]
wherein T s (sec) is the time required for an amount of a 0.9% saline solution to permeate a saline-absorbed super absorbent polymer under a load of 0.3 psi, wherein the saline-absorbed super absorbent polymer is prepared by swelling 0.2 g of super absorbent polymer powder with the 0.9% saline solution for 30 minutes, and
T 0 (sec) is the time required for the amount of the 0.9% saline solution to flow under the load of 0.3 psi in the absence of the saline-absorbed super absorbent polymer,
wherein the surface crosslinking is performed for 15 to 90 minutes at a temperature ranging from 180 to 200° C. using a surface crosslinking solution including a surface crosslinking agent.
2. The super absorbent polymer of claim 1 , wherein the water-soluble component having a ratio (dwt/d(log M)) of 0.9 or less over molecular weights (M) ranging from 100,000 to 300,000 g/mol, when measured from an eluted solution after free swelling 1 g of the super absorbent polymer in 200 ml of a 0.9% NaCl solution for 1 hour.
3. The super absorbent polymer of claim 1 , wherein a centrifuge retention capacity (CRC) ranges from about 26 to about 32 g/g.
4. The super absorbent polymer of claim 1 , wherein an absorbency under load (0.7 psi AUL) ranges from about 20 to about 26 g/g.
5. A hygiene product including the super absorbent polymer of claim 1 .
6. A disposable diaper including the super absorbent polymer of claim 1 .