US 12,269,009 B2
Super absorbent polymer and method for preparing same
Hyemi Nam, Daejeon (KR); Sang Gi Lee, Daejeon (KR); Yeonsoo Kim, Daejeon (KR); and Chang Hun Lee, Daejeon (KR)
Assigned to LG Chem, Ltd., Seoul (KR)
Appl. No. 17/258,660
Filed by LG Chem, Ltd., Seoul (KR)
PCT Filed Jan. 17, 2020, PCT No. PCT/KR2020/000852
§ 371(c)(1), (2) Date Jan. 7, 2021,
PCT Pub. No. WO2020/149691, PCT Pub. Date Jul. 23, 2020.
Claims priority of application No. 10-2019-0006228 (KR), filed on Jan. 17, 2019; and application No. 10-2020-0006215 (KR), filed on Jan. 16, 2020.
Prior Publication US 2021/0268475 A1, Sep. 2, 2021
Int. Cl. B01J 20/26 (2006.01); B01J 20/30 (2006.01)
CPC B01J 20/267 (2013.01) [B01J 20/261 (2013.01); B01J 20/3021 (2013.01); B01J 20/3078 (2013.01); B01J 2220/68 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for preparing a super absorbent polymer comprising:
polymerizing a monomer composition including an acrylic acid-based monomer having at least partially neutralized acidic groups, a foaming agent, an internal crosslinking agent, and a polymerization initiator to form a hydrogel polymer;
chopping the hydrogel polymer through a chopper containing two or more hole plates arranged in series with a screw therethrough;
drying, pulverizing and classifying the chopped hydrogel polymer to form a base polymer; and
further crosslinking a surface of the base polymer powder in the presence of a surface crosslinking agent to form a surface crosslinked layer,
wherein each of the two or more hole plates comprises a plurality of holes,
wherein an average diameter of the plurality of holes of each successive hole plate becomes smaller with each successive hole plate in a direction away from an inlet to the screw;
wherein the hydrogel polymer is pulverized while being pushed out of each hole plate by the screw while being continuously pushed out by the screw in subsequent hole plates in decreasing particle size, and
wherein the super absorbent polymer has an absorption rate (vortex) of 40 seconds or less calculated by measuring in seconds an amount of time required for a vortex to disappear after adding 2 g of a super absorbent polymer to 50 mL of physiological saline solution at 23° C. to 24° C. and then stirring at 600 rpms.