Preparation Method of Super Absorbent Polymer

A preparation method of a super absorbent polymer, comprising:

• preparing a monomer mixture comprising a water-soluble ethylene-based unsaturated monomer having at least partially neutralized acidic groups and an internal cross-linking agent;
• transferring the monomer mixture to a polymerization reactor;
• during the transferring the monomer mixture to the polymerization reactor, adjusting a dynamic pressure applied to the monomer mixture being transferred calculated by the following Equation 1 to 140 Pa or more by controlling a transfer rate;
• cross-linking and polymerizing the monomer mixture transferred to the polymerization reactor to form a hydrogel polymer;
• drying, pulverizing and classifying the hydrogel polymer to form a base resin powder;
• and
• further cross-linking a surface of the base resin powder in the presence of a surface cross-linking agent to form a surface cross-linked layer:
• Dynamic pressure=1/2*p*V2 [Equation 1]
• in Equation 1, p denotes a density (g/cm3) of the monomer mixture being transferred, and V denotes a transfer rate (m/s) of the monomer mixture.