Super absorbent polymer and method for producing same

Patent metadata

Field	Value
Publication number	US-2020009529-A1
Application number	US-201716062778-A
Country	US
Kind code	A1
Filing date	Apr 12, 2017
Priority date	Oct 12, 2016
Publication date	Jan 9, 2020
Grant date	—

Abstract

The present invention relates to an olefin polymer and a method for producing the same. 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

1 . A super absorbent polymer; comprising:
a base polymer powder including a cross-linked polymer in which a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups is cross-linked in the presence of an internal crosslinking agent; and first and second surface cross-linked layers that are further cross-linked from the cross-linked polymer in the presence of a surface crosslinking agent and are formed on the base polymer powder, 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, and 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 a super absorbent polymer,
0.3 AGBP is a gel bed permeability (GBP) under 0.3 psi for a physiological saline solution of a 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.

5 . A super absorbent polymer; comprising: a base polymer powder including a cross-linked polymer in which a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups is cross-linked in the presence of an internal crosslinking agent; and
first and second surface cross-linked layers that are further cross-linked from the cross-linked polymer in the presence of a surface crosslinking agent and are formed on the base polymer powder, wherein the first and second surface cross-linked layers each include a cross-linked structure derived from surface crosslinking agents that are different from each other; and having: an absorbency under load (AUL) under 0.9 psi for a physiological saline solution of 19 to 25 g/g, and 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 a super absorbent polymer,
0.3 AGBP is a gel bed permeability (GBP) under 0.3 psi for a physiological saline solution of a 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.

6 . A method for producing a super absorbent polymer comprising the steps of:
carrying out a crosslinking polymerization of a monomer mixture including a water-soluble ethylenically unsaturated monomer having at least partially neutralized acidic groups in the presence of an internal crosslinking agent to form a hydrogel polymer; drying, pulverizing and classifying the hydrogel polymer to form a base polymer powder; and subjecting the surface of the base polymer powder to a first crosslinking in the presence of an epoxy-based surface crosslinking agent and then subjecting the surface of the first cross-linked base polymer powder to a second crosslinking in the presence of a non-epoxy-based surface crosslinking agent to form a surface crosslinked layer, wherein a GBP change ratio of the super absorbent polymer calculated by the following Formula 1 is 0.90 or less.

0.3



GBP

-

0.3



AGBP

0.3



GBP

Assignees

• Lg Chemical Ltd

Inventors

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

Classifications

• C08F220/06

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

• C08J2333/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• B01J20/3085

  Chemical treatments not covered by groups B01J20/3007 - B01J20/3078 · CPC title

• B01J20/3021

  Milling, crushing or grinding · CPC title

• A61L15/24

  Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof {(A61L15/225 takes precedence)} · CPC title