	US 11,918,978 B2
	Method of preparing superabsorbent polymer
Seul Ah Lee, Daejeon (KR); Gicheul Kim, Daejeon (KR); Dae Woo Nam, Daejeon (KR); Ki Hyun Kim, Daejeon (KR); Jun Kyu Kim, Daejeon (KR); and Young Jae Hur, Daejeon (KR)
Assigned to LG Chem, Ltd., (KR)
Appl. No. 16/982,292
Filed by LG Chem, Ltd., Seoul (KR)
PCT Filed Dec. 10, 2019, PCT No. PCT/KR2019/017396 § 371(c)(1), (2) Date Sep. 18, 2020, PCT Pub. No. WO2020/122559, PCT Pub. Date Jun. 18, 2020.
Claims priority of application No. 10-2018-0158524 (KR), filed on Dec. 10, 2018; and application No. 10-2019-0163106 (KR), filed on Dec. 9, 2019.
Prior Publication US 2021/0023529 A1, Jan. 28, 2021
Int. Cl. C08F 220/06 (2006.01); B01J 20/26 (2006.01); C08F 2/44 (2006.01); C08J 3/12 (2006.01); C08J 9/14 (2006.01); C08J 9/16 (2006.01); C08J 9/28 (2006.01); C08L 23/02 (2006.01); C08L 25/02 (2006.01); C08L 27/02 (2006.01); C08L 31/04 (2006.01); C08L 33/08 (2006.01); C08L 33/20 (2006.01)

CPC B01J 20/261 (2013.01) [C08F 2/44 (2013.01); C08F 220/06 (2013.01); C08J 3/12 (2013.01); C08J 9/14 (2013.01); C08J 9/16 (2013.01); C08L 23/02 (2013.01); C08L 25/02 (2013.01); C08L 27/02 (2013.01); C08L 31/04 (2013.01); C08L 33/08 (2013.01); C08L 33/20 (2013.01); B01J 2220/68 (2013.01); C08L 2207/53 (2013.01); C08L 2312/00 (2013.01)]

10 Claims

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.