Super absorbent polymer and preparation method thereof

Patent metadata

Field	Value
Publication number	US-9808787-B2
Application number	US-201615286764-A
Country	US
Kind code	B2
Filing date	Oct 6, 2016
Priority date	Sep 30, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

The present invention relates to a super absorbent polymer and a preparation method thereof. The super absorbent polymer includes surface crosslinked polymer particles prepared by surface crosslinking of particles of a base resin, wherein the base resin is polymerized from a monomer composition including water-soluble ethylene-based unsaturated monomers, and a water-soluble component, wherein the water-soluble component has a ratio (dwt/d(log M)) of 0.9 or less over molecular weights (M) ranging from 100,000 to 300,000 when measured from an eluted solution after swelling the super absorbent polymer for 1 hour, and wherein the content of the water-soluble component is 5% by weight or less, based on the total weight of the super absorbent polymer, when measured after swelling the super absorbent polymer for 1 hour. The super absorbent polymer has excellent liquid permeability even when swollen without a reduction in centrifuge retention capacity or absorbency under load while having improved permeability.

First claim

What is claimed is:

1. A preparation method of a super absorbent polymer, comprising:
heating or irradiating a monomer composition to form a hydrogel polymer by polymerization, wherein the monomer composition contains water-soluble ethylene-based unsaturated monomers and a polymerization initiator;
drying the hydrogel polymer;
pulverizing the dried polymer to form particles; and
heating a mixture of the particles and a surface crosslinking solution at a temperature ranging from about 180 to about 200° C. to form surface crosslinked polymer particles of the super absorbent polymer,
wherein the surface crosslinking solution contains a surface crosslinking agent and water,
wherein the super absorbent polymer includes a water-soluble component having a ratio (dwt/d(log M)) of 0.86 or less over an entire range of molecular weight ranging from 100,000 to 300,000 when measured from an eluted solution after swelling 1 g of the super absorbent polymer in 200 ml of 0.9% NaCl solution at 25° C. for 1 hour, and
wherein the water-soluble component is present in an amount of 5% by weight or less, based on the total weight of the super absorbent polymer, when measured from an eluted solution after swelling 1 g of the super absorbent polymer in 200 ml of 0.9% NaCl solution at 25° C. for 1 hour.

2. The preparation method of claim 1 , wherein the monomer composition includes a internal crosslinking agent.

3. The preparation method of claim 2 , wherein the internal cross linking agent is present in an amount ranging from 0.1 to 0.5 wt % based on the monomer composition.

Assignees

• Lg Chemical Ltd

Inventors

• Ryu Chul Hee
• Lee Hyemin

Classifications

• C08J2333/02

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

• B01J20/3078

  Thermal treatment, e.g. calcining or pyrolizing · CPC title

• C08F2/10 Primary

  Aqueous solvent · CPC title

• C08L101/14

  the macromolecular compounds being water soluble or water swellable, e.g. aqueous gels · CPC title

• B01J2220/68

  Superabsorbents · CPC title