Method for preparing super absorbent polymer

Patent metadata

Field	Value
Publication number	US-11969707-B2
Application number	US-201917045025-A
Country	US
Kind code	B2
Filing date	Nov 8, 2019
Priority date	Nov 13, 2018
Publication date	Apr 30, 2024
Grant date	Apr 30, 2024

Abstract

The method for preparing a super absorbent polymer according to the present disclosure has a feature that it is possible to reduce the generation of a fine powder during production of the super absorbent polymer while maintaining excellent physical properties of the super absorbent polymer, including centrifuge retention capacity (CRC) and vortex removal time.

First claim

The invention claimed is:

1. A method for preparing a super absorbent polymer comprising:
performing crosslinking polymerization of a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized, in the presence of an internal crosslinking agent and a polymerization initiator to form a hydrogel polymer containing a first erosslinked polymer;
drying the hydrogel polymer so that a water content of the polymer is 2 to 10 wt %; and
pulverizing the dried polymer to prepare particles,
wherein the internal crosslinking agent is used in an amount of 500 to 2500 ppmw based on a weight of the water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized,
wherein the crosslinking polymerization is performed in the presence of a foaming agent, and
wherein the foaming agent is an encapsulated foaming agent, which has a structure including a core containing hydrocarbon and a shell surrounding the core and formed of a thermoplastic resin.

2. The method of claim 1 ,
wherein the internal crosslinking agent is ethylene glycol diglycidyl ether, N,N′-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, polyethylene glycol diacrylate, ethylene glycol di(meth)acrylate, polyethylene glycol(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, butanediol di(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentacrylate, glycerin tri(meth)acrylate, pentaerythritol tetraacrylate, triarylamine, propylene glycol, glycerin, or ethylene carbonate.

3. The method of claim 1 ,
wherein the internal crosslinking agent is used in an amount of 800 to 2000 ppmw, based on the weight of the water-soluble ethylenically unsaturated monomer having an acidic group in which at least a portion is neutralized.

4. The method of claim 1 ,
wherein the encapsulated foaming agent has an average diameter of 5 to 50 μm.

5. The method of claim 1 ,
wherein the drying the hydrogel polymer is performed at a temperature of 90 to 195° C.

6. The method of claim 1 ,
wherein the drying the hydrogel polymer is performed at a temperature of 100 to 140° C.

7. The method of claim 1 ,
wherein the particles are classified into particles having a particle diameter of 150 μm to 850 μm.

8. The method of claim 1 ,
further comprising crosslinking the surface of the particles.

9. The method of claim 8 ,
wherein the surface crosslinking is performed at a temperature of 120 to 160° C.

10. The method of claim 8 ,
wherein the surface crosslinking is performed at a temperature of 135 to 145° C.

11. A method for preparing a super absorbent polymer, comprising:
performing crosslinking polymerization of a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized, in the presence of an internal crosslinking agent and a polymerization initiator to form a hydrogel polymer containing a first crosslinked polymer;
drying the hydrogel polymer so that a water content of the polymer is 2 to 10 wt %; and
pulverizing the dried polymer to prepare particles,
wherein the internal crosslinking agent is used in an amount of 500 to 2500 ppmw based on a weight of the water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized, further comprising crosslinking the surface of the particles, and wherein the surface crosslinking is performed at a temperature of 120 to 160° C.

12. The method of claim 1 ,
wherein the foaming agent is used in an amount of 100 to 1500 ppmw based on the weight of the water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized.

Assignees

• Lg Chemical Ltd

Inventors

• Kim Jaeyul
• Song Jong Hun
• Kim Gicheul
• Min Yoon Jae
• Kim Ki Hyun
• Lee Seul Ah
• Jeong In Yong
• Woo Heechang

Classifications

• B01J20/261 Primary

  obtained by reactions only involving carbon to carbon unsaturated bonds (macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds per se C08F) · CPC title

• B01J20/267

  Cross-linked polymers · CPC title

• C08F2/48

  by ultraviolet or visible light · CPC title

• C08F120/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• C08F222/102

  of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate · CPC title