Preparation Method of Super Absorbent Polymer and Super Absorbent Polymer Prepared Therefrom

Patent metadata

Field	Value
Publication number	US-2022016599-A1
Application number	US-202017413793-A
Country	US
Kind code	A1
Filing date	May 4, 2020
Priority date	May 7, 2019
Publication date	Jan 20, 2022
Grant date	—

Abstract

The present disclosure relates to a method for preparing a super absorbent polymer that enables the preparation of a more improved super absorbent polymer even without excessive use of a surfactant and use of a foaming agent, and a super absorbent polymer prepared therefrom which exhibits a superior absorption rate.

First claim

1 . A method for preparing a super absorbent polymer comprising:
performing crosslinking polymerization of a monomer mixture including a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized, an anionic surfactant having an HLB value of 20 to 40 and an internal crosslinking agent to form a hydrogel polymer; drying, pulverizing and classifying the hydrogel polymer to form a base polymer powder; and further cross-linking the surface of the base polymer powder in the presence of a surface crosslinking agent to form a surface cross-linked layer, wherein the anionic surfactant is used at a concentration of 50 to 200 ppmw in the monomer mixture, and wherein the monomer mixture is formed by a method comprising mixing a solution containing the anionic surfactant with a mixture containing the monomer and the internal crosslinking agent while passing the solution through a tubular flow channel having a plurality of projecting pins therein at a space velocity of 50 to 1500 (min −1 ).

2 . The method for preparing a super absorbent polymer according to claim 1 , wherein the anionic surfactants comprises one or more of sodium dodecyl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, dioctyl sodium sulfosuccinate, perfluorooctane sulfonate, perfluorobutane sulfonate, alkyl-aryl ether phosphate, alkyl ether phosphate, sodium myreth sulfate or carboxylate salt.

3 . The method for preparing a super absorbent polymer according to claim 1 , wherein the monomer mixture further includes 0.1% by weight or less of a nonionic surfactant having an HLB value of 4 to 15.

4 . The method for preparing a super absorbent polymer according to claim 3 , wherein the nonionic surfactant is one or more selected from the group consisting of fatty acid ester, sorbitan trioleate, polyethoxylated sorbitan monooleate, sorbitan monooleate and sugar ester.

5 . The method for preparing a super absorbent polymer according to claim 3 , further comprising:
forming a primary mixture in a solution state containing the water-soluble ethylenically unsaturated monomer and the internal crosslinking agent; mixing the primary mixture with a basic aqueous solution to form a secondary mixture in which at least a part of the acid groups of the unsaturated monomer is neutralized; and mixing a solution containing the nonionic surfactant having an HLB value of 4 to 15, and a solution containing an initiator, other additives and the anionic surfactant with the secondary mixture while passing the above solutions through the tubular flow channel having the plurality of projecting pins therein at the space velocity of 50 to 1500 (min −1 ).

6 . The method for preparing a super absorbent polymer according to claim 5 , wherein mixing the solution containing the anionic surfactant further comprises supplying and mixing an aqueous solution containing the anionic surfactant at a concentration of 0.1 to 0.3% by weight.

7 . The method for preparing a super absorbent polymer according to claim 1 , wherein the crosslinking polymerization of the hydrogel polymer is performed by solution polymerization with respect to the monomer mixture in an aqueous solution state.

8 . A super absorbent polymer comprising:
a base polymer powder including a first cross-linked polymer of a water-soluble ethylenically unsaturated monomer having an acidic group of which at least a part is neutralized; and a surface crosslinked layer formed on the base polymer powder in which the first cross-linked polymer is further crosslinked via a surface crosslinking agent, wherein the super absorbent polymer has an absorption rate (vortex time) measured by a vortex test method of 5 to 35 seconds, a surface tension of 65 to 72 mN/m, and a bulk density of 0.50 to 0.65 g/ml.

9 . The super absorbent polymer according to claim 8 , wherein the super absorbent polymer has a particle size of 150 to 850 μm, contains particles having a particle size of 600 μm or more in an amount of 12 wt % or less, and contains particles having a particle size of 300 μm or more in an amount of 20 wt % or less.

10 . The super absorbent polymer according to claim 8 , wherein the super absorbent polymer has a centrifuge retention capacity (CRC) of 25 to 35 g/g as measured according to EDANA recommended test method WSP 241.3.

11 . The super absorbent polymer according to claim 8 , wherein the super absorbent polymer has an absorbency under load (AUL) at 0.9 psi of 16 to 23 g/g as measured according to EDANA recommended test method WSP 242.3.

12 . The super absorbent polymer according to claim 8 , wherein the super absorbent polymer has a gel bed permeability (GBP) of 25 to 50 darcy.

Assignees

• Lg Chemical Ltd

Inventors

• Lee Sang Gi
• Kim Mookon
• Lee Yong Hun
• Nam Hyemi
• Jeong Jiyoon
• Lee Chang Hun

Classifications

• C08J2333/02

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

• C08J3/245 Primary

  Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking · CPC title

• C08J3/075

  Macromolecular gels · CPC title

• C08F2810/20

  leading to a crosslinking, either explicitly or inherently · CPC title

• C08F20/06

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