Patent ID: 11891487
Assignee: LG CHEM, LTD.
Field: Other special machines (Mechanical engineering)
Classification: CPC C | IPC C

Claim 0:
1. A preparation method of a super absorbent polymer, comprising:
forming a hydrogel polymer by cross-linking and polymerizing a monomer composition comprising a water-soluble ethylene-based unsaturated monomer having at least partially neutralized acidic groups and an internal cross-linking agent;
drying, pulverizing and classifying the hydrogel polymer to form a base resin powder;
forming a surface cross-linked layer by further cross-linking a surface of the base resin powder in the presence of a surface cross-linking agent; and
additionally neutralizing the base resin powder by treating the base resin powder with a basic solution after the forming of the surface cross-linked layer, to form the super absorbent polymer;
wherein the water-soluble ethylene-based unsaturated monomer has a degree of neutralization of less than 72 mol % during the forming of the hydrogel polymer,
wherein extractable components of the super absorbent polymer have a degree of neutralization of greater than 70 mol % to 80 mol %,
wherein the degree of neutralization of the extractable components of the super absorbent polymer is greater than the degree of neutralization of the monomer,
wherein the basic solution is used in an amount of 1 to 10 parts by weight based on 100 parts by weight of the base resin powder.