Super absorbent polymer and method for producing same

Patent metadata

Field	Value
Publication number	US-10850260-B2
Application number	US-201716062778-A
Country	US
Kind code	B2
Filing date	Apr 12, 2017
Priority date	Oct 12, 2016
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A super absorbent polymer and a method for producing the same are disclosed herein. In some embodiments, the super absorbent polymer includes a base polymer powder including a cross-linked polymer, and first and second surface cross-linked layers formed on the base polymer powder. The first and second surface cross-linked layers are formed by further cross-linking the cross-linked polymer in the presence of a surface crosslinking agent, wherein the first and second surface cross-linked layers each include a cross-linked structure derived from epoxy-based and non-epoxy-based surface crosslinking agents. The super absorbent polymer can exhibit excellent absorbent properties even in a swollen state and thus exhibit excellent anti-rewetting effects. Accordingly, when the super absorbent polymer is used, it is possible to provide a sanitary material such as a diaper or a sanitary napkin which can give a smooth touch feeling even after the body fluid is discharged.

First claim

The invention claimed is:

1. A super absorbent polymer, comprising:
a base polymer powder including a cross-linked polymer polymerized from a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups and cross-linked in the presence of an internal crosslinking agent; and
first and second surface cross-linked layers formed on the base polymer powder, the first and second surface cross-linked layers formed by further cross-linking the cross-linked polymer in the presence of a surface crosslinking agent,
wherein the first and second surface cross-linked layers each include a cross-linked structure derived from epoxy-based and non-epoxy-based surface crosslinking agents,
wherein the first surface cross-linked layer includes at least one polyvalent metal cation and optionally an inorganic material,
and
wherein the superabsorbent polymer having a GBP change ratio calculated by the following Formula 1 of 0.90 or less,

0.3
⁢

⁢
GBP

-

0.3
⁢

⁢
AGBP

0.3
⁢

⁢
GBP

[

Formula
⁢

⁢
1

]

in Formula 1,
0.3 GBP is a gel bed permeability (GBP) under 0.3 psi for a 0.9 wt % sodium chloride aqueous solution of the super absorbent polymer,
0.3 AGBP is a gel bed permeability (AGBP) under 0.3 psi for a physiological saline solution of the super absorbent polymer having a particle size from 300 to 600 μm after swelling and drying which is obtained by a process of adding 5 g of the super absorbent polymer to 125 g of distilled water, stirring the resultant for 1 minute, drying the swollen super absorbent polymer at 100° C. for 3 hours, and then classifying the dried polymer through a U.S. standard 30 mesh screen and a U.S. standard 50 mesh screen.

2. The super absorbent polymer of claim 1 , wherein it has a centrifuge retention capacity for a physiological saline solution of 30 to 40 g/g.

3. The super absorbent polymer of claim 1 , wherein it has an absorbency under load under 0.9 psi for a physiological saline solution of 19 to 25 g/g.

4. The super absorbent polymer of claim 1 , wherein it has a free swell gel bed permeability for a physiological saline solution of about 50 darcy to about 100 darcy.

Assignees

• Lg Chemical Ltd

Inventors

• Nam Hye Mi
• Lee Sang Gi
• Hwang Min Ho
• Lee Soo Jin
• Han Chang Sun

Classifications

• C08K5/1515

  Three-membered rings · CPC title

• C08K5/06

  Ethers; Acetals; Ketals; Ortho-esters · CPC title

• C08K5/053

  Polyhydroxylic alcohols · CPC title

• C08K5/0025

  Crosslinking or vulcanising agents; including accelerators · CPC title

• C08J2300/14

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