Method for preparing super absorbent polymer

A method for preparing a super absorbent polymer, comprising:

• preparing a hydrogel polymer by polymerizing a monomer composition comprising a water-soluble ethylene-based unsaturated monomer having at least partially neutralized acidic groups and a polymerization initiator;
• drying and pulverizing the hydrogel polymer, and performing classification into fines having a particle diameter of less than 150 μm and normal particles having a particle diameter of 150 to 850 μm;
• preparing a fine reassembly by mixing the fines with water and a polycarboxylic acid-based copolymer, followed by reassembling;
• preparing an extruded fine reassembly by extruding the fine reassembly while adding water, followed by drying, pulverization and classification;
• and
• mixing the extruded fine reassembly with the normal particles, and then performing a surface cross-linking reaction by adding a surface cross-linking agent;
• wherein 30 to 80 parts by weight of water are used based on 100 parts by weight of the fines in the preparation of the fine reassembly, and
• 15 to 30 parts by weight of water are used based on the fine reassembly in the preparation of the extruded fine reassembly,
• wherein the polycarboxylic acid-based copolymer is a copolymer comprising at least one of a repeating unit represented by the following Chemical Formula 1-a or a repeating unit represented by the following Chemical Formula 1-b:
• wherein, in Chemical Formulae 1-a and 1-b,
• R1, R2 and R3 are each independently hydrogen or a C1 to C6 alkyl group,
• RO is a C2 to C4 oxyalkylene group,
• M1 is hydrogen, or a monovalent metal or non-metal ion,
• X is —COO—, a C1 to C5 alkyloxy group, or a C1 to C5 alkyldioxy group,
• m is an integer of 1 to 100,
• n is an integer of 1 to 1000, and
• p is an integer of 1 to 150, and when p is 2 or more, two or more repeating —RO— are the same as or different from each other.