Super absorbent polymer and method for preparing same

Patent metadata

Field	Value
Publication number	US-10711074-B2
Application number	US-201816319057-A
Country	US
Kind code	B2
Filing date	Jan 23, 2018
Priority date	Jan 23, 2017
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

The present invention relates to a super absorbent polymer and a method for preparing the same. According to the super absorbent polymer and the method for preparing a super absorbent polymer of the present invention, a laponite is contained in a colloidal solution state during polymerization of the monomer composition, and thus achieves an appropriate crosslinking density, thereby contributing to improvement of various physical properties such as a gel strength and a centrifuge retention capacity of the super absorbent polymer.

First claim

What is claimed is:

1. A method for preparing a super absorbent polymer comprising:
preparing a monomer composition containing a water soluble ethylenically unsaturated monomer, an internal crosslinking agent, and a polymerization initiator;
mixing the monomer composition with a laponite colloidal solution containing 0.02 to 0.09 part by weight of a positively charged laponite based on 100 parts by weight of the monomer composition to form a mixture of the monomer composition and the lapnotie colloidal solution; and
thermally polymerizing or photo-polymerizing the mixture of the monomer composition and the laponite colloidal solution to form a crosslinked polymer.

2. The method for preparing a super absorbent polymer according to claim 1 , wherein the laponite colloidal solution includes laponite in the concentration of 0.5% to 10% by weight.

3. The method for preparing a super absorbent polymer according to claim 1 , wherein the laponite colloidal solution has a viscosity of 1.2 to 10 cps at 25° C.

4. The method for preparing a super absorbent polymer according to claim 1 , wherein a charge amount of the laponite is 1 to 10 mmol/100 g.

5. The method for preparing a super absorbent polymer according to claim 1 , wherein the positively charged laponite includes at least one of Laponite XLG, Laponite RD, Laponite EP, Laponite XL21, or Laponite D.

6. The method for preparing a super absorbent polymer according to claim 1 , wherein the crosslinked polymer satisfies the following Formula 1:
4.00≤GSI(Gel strength index)≤4.20  [Formula 1]

wherein, GSI=(gel strength of the crosslinked polymer (unit: Pa)+9,750*In (centrifuge retention capacity (CRC, unit: g/g) measured according to EDANA method WSP 241.3)/10,000.

7. The method for preparing a super absorbent polymer according to claim 6 , wherein the crosslinked polymer has a centrifuge retention capacity (CRC) of 35 to 45 g/g, measured according to EDANA method WSP 241.3.

8. The method for preparing a super absorbent polymer according to claim 6 , wherein the crosslinked polymer has a gel strength of 2,500 to 5,000 Pa.

9. The method for preparing a super absorbent polymer according to claim 1 , wherein the crosslinked polymer has an absorption under pressure (AUP) of 20 to 30 g/g, measured under 0.7 psi according to EDANA method WSP 242.3.

10. The method for preparing a super absorbent polymer according to claim 1 , wherein the internal crosslinking agent is polyethylene glycol diacrylate.

11. A super absorbent polymer comprising: a crosslinked polymer formed by polymerizing a mixture of a monomer composition containing a water soluble ethylenically unsaturated monomer, an internal crosslinking agent, and a polymerization initiator; and a laponite colloidal solution containing 0.02 to 0.09 part by weight of a positively charged laponite based on 100 parts by weight of the monomer composition.

12. The super absorbent polymer according to claim 11 , wherein the crosslinked polymer satisfies the following Formula 1:
4.00≤GSI(Gel strength index)=4.20  [Formula 1]

wherein, GSI=(gel strength of the crosslinked polymer (unit: Pa)+9,750*In (centrifuge retention capacity (CRC, unit: g/g) measured according to EDANA method WSP 241.3)/10,000.

13. The super absorbent polymer according to claim 12 , wherein the crosslinked polymer has a centrifuge retention capacity (CRC) of 35 to 45 g/g, measured according to EDANA method WSP 241.3.

14. The super absorbent polymer according to claim 12 , wherein the crosslinked polymer has a gel strength of 2,500 to 5,000 Pa.

15. The super absorbent polymer according to claim 11 , wherein the crosslinked polymer has an absorption under pressure (AUP) of 20 to 30 g/g, measured under 0.7 psi according to EDANA method WSP 242.3.

16. The super absorbent polymer according to claim 11 , wherein the internal crosslinking agent is polyethylene glycol diacrylate.

17. The super absorbent polymer according to claim 11 , wherein a charge amount of the positively charged laponite is 1 to 10 mmol/100 g.

18. The super absorbent polymer according to claim 11 , wherein the positively charged laponite includes at least one Laponite XLG, Laponite RD, Laponite EP, Laponite XL21, or Laponite D.

19. The super absorbent polymer according to claim 11 , further comprising a surface crosslinked layer formed on the surface of the crosslinked polymer.

Assignees

• Lg Chemical Ltd

Inventors

• Kim Ju Eun
• Kim Gi Cheul
• Park Sung Soo

Classifications

• C08K3/346

  Clay · CPC title

• C08F2/44 Primary

  Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers · CPC title

• C08J3/24 Primary

  Crosslinking, e.g. vulcanising, of macromolecules (mechanical aspects B29C35/00; crosslinking agents C08K) · CPC title

• C08J2300/14

  Water soluble or water swellable polymers, e.g. aqueous gels · CPC title

• C08K2201/011

  Nanostructured additives · CPC title