Method for producing superabsorbent particles

Patent metadata

Field	Value
Publication number	US-12350647-B2
Application number	US-202017419333-A
Country	US
Kind code	B2
Filing date	Jan 13, 2020
Priority date	Jan 24, 2019
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A process for producing superabsorbent particles, comprising polymerization of a monomer preparation, drying of the resultant aqueous polymer gel, grinding, classifying and thermal surface postcrosslinking, wherein the monomer preparation is produced by mixing an aqueous monomer solution and a foamed aqueous surfactant solution.

First claim

The invention claimed is:

1. A process for producing superabsorbent particles, comprising:
foaming an aqueous surfactant solution to form a foamed aqueous surfactant solution;
mixing the foamed aqueous surfactant solution with an aqueous monomer solution to obtain a monomer preparation, the aqueous monomer solution comprising:
a) at least one ethylenically unsaturated monomer which bears an acid group and is at least partly neutralized,
b) at least one crosslinker and
c) at least one initiator; and

polymerizing the monomer preparation, drying a resultant aqueous polymer gel, grinding, classifying and thermal surface postcrosslinking.

2. The process according to claim 1 , wherein polymerizing of the monomer preparation is conducted in a kneading reactor and the aqueous monomer solution and the foamed aqueous surfactant solution are mixed in the kneading reactor.

3. The process according to claim 1 , wherein the polymerizing is conducted in a continuous kneading reactor.

4. The process according to claim 1 , wherein the aqueous monomer solution comprises from 40% to 50% by weight of the monomer a).

5. The process according to claim 1 , wherein the monomer a) has been neutralized to an extent of 60 to 80 mol %.

6. The process according to claim 1 , wherein the monomer a) is partly neutralized acrylic acid.

7. The process according to claim 1 , wherein the foamed aqueous surfactant solution comprises from 1% to 3% by weight of at least one surfactant.

8. The process according to claim 1 , wherein the foamed aqueous surfactant solution comprises at least one nonionic surfactant.

9. The process according to claim 1 , wherein a weight ratio of the foamed aqueous surfactant solution to the aqueous monomer solution in the monomer preparation is from 0.03 to 0.10.

10. The process according to claim 1 , wherein the foamed aqueous surfactant solution additionally comprises a water-soluble polymer.

11. The process according to claim 10 , wherein the foamed aqueous surfactant solution comprises from 5% to 10% by weight of the additional water-soluble polymer.

12. The process according to claim 10 , wherein the additional water-soluble polymer is polyethylene glycol.

13. The process according to claim 1 , wherein the at least one initiator c) is a redox initiator.

Assignees

• Basf Se

Inventors

• Haag Monica
• Gierescher Stefan

Classifications

• B01J20/3085

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

• B01J20/3021

  Milling, crushing or grinding · CPC title

• B01J20/28016

  Particle form · CPC title

• B01J20/262

  obtained otherwise than by reactions only involving carbon to carbon unsaturated bonds, e.g. obtained by polycondensation (macromolecular compounds obtained otherwise than by reactions only involving unsaturated carbon-to-carbon bonds per se C08G) · CPC title

• A61L15/60

  Liquid-swellable gel-forming materials, e.g. super-absorbents · CPC title