Patent ID: 11918978
Assignee: LG CHEM, LTD.
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC B  C | IPC B  C

Claim 0:
1. A method of preparing a superabsorbent polymer, comprising:
preparing a monomer composition by mixing water-soluble ethylenically unsaturated monomers comprising (meth)acrylic acid with a basic material comprising potassium hydroxide, an encapsulated foaming agent, an internal crosslinking agent, and a polymerization initiator, wherein at least part of the acidic groups of the water-soluble ethylenically unsaturated monomers is neutralized with the basic material comprising potassium hydroxide;
forming a water-containing gel polymer by performing thermal polymerization or photo-polymerization of the monomer composition;
forming a base polymer in the form of powder by drying and pulverizing the water-containing gel polymer; and
forming a surface-crosslinked layer by additionally crosslinking a surface of the base polymer in the presence of a surface crosslinking agent,
wherein the encapsulated foaming agent has a structure including a core which contains a hydrocarbon and a shell which surrounds the core and is formed using a thermoplastic resin, and has a mean diameter of 5 μm to 30 μm before expansion and a maximum expansion ratio of 5 times to 15 times in air.