Super absorbent polymer and method for preparing the same

Patent metadata

Field	Value
Publication number	US-11325101-B2
Application number	US-201615556740-A
Country	US
Kind code	B2
Filing date	Nov 17, 2016
Priority date	Feb 25, 2016
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

The present invention relates to a super absorbent polymer having not only excellent absorption rate and absorbency under load but also excellent rewetting properties, and a method for preparing the same.

First claim

The invention claimed is:

1. A super absorbent polymer comprising:
a base polymer powder containing a first crosslinked polymer of a water-soluble ethylene-based unsaturated monomer having an acidic group in which at least a part thereof is neutralized; and
a surface-crosslinked layer containing a second crosslinked polymer formed on the base polymer powder in which the first crosslinked polymer is additionally crosslinked via a surface crosslinking agent,
wherein the superabsorbent polymer is prepared by:

1) performing thermal polymerization or photopolymerization of a monomer composition comprising the water-soluble ethylene-based unsaturated monomer having the acidic group in which at least the part thereof is neutralized, a carbonate forming agent, an anionic surfactant and a polymerization initiator to form a hydrogel polymer, wherein the anionic surfactant is dioctyl sodium sulfosuccinate,
2) drying the hydrogel polymer,
3) pulverizing the dried polymer, and
4) performing surface cros slinking reaction of the pulverized polymer; and
wherein the super absorbent polymer has:
an average particle diameter of 300 μm to 600 μm,
CRC of 28 g/g to 35 g/g,
AUL (0.9 psi) of 18 g/g to 25 g/g,
10-min WAUL of 15 g/g to 25 g/g,
a gel bed permeability (GBP) for a physiological saline solution of 30 darcy or more,
5-min Gel-Vacuum AUL of 18 g/g to 25 g/g, and
a vortex time of 5 seconds to 50 seconds,
wherein
the WAUL is measured according to the following Equation 1:
WAUL(g/g)=[W 2 (g)−W 1 (g)]/ W 0 (g)   [Equation 1]

in Equation 1,
W 0 (g) is an initial weight(g) of the super absorbent polymer,
W 1 (g) is the total sum of a weight of the super absorbent polymer and a weight of the device capable of providing a load to the super absorbent polymer,
W 2 (g) is the total sum of a weight of the super absorbent polymer and a weight of the device capable of providing a load to the super absorbent polymer, after absorbing a physiological saline solution below 15 cm from the super absorbent polymer under a load (0.7 psi) for 10 minutes,
wherein the vortex time means the amount of time required until the vortex disappears after adding 2 g of a super absorbent polymer to 50 mL of physiological saline solution and then stirring the mixture at 600 rpm, and
wherein
the 5-min Gel-Vacuum AUL is measured according to the following Equation 5:
5-min Gel-Vacuum AUL(g/g)=[W 8 (g)−W 7 (g)]/ W 0 (g)   [Equation 5]

in Equation 5,
W 0 (g) is an initial weight(g) of the super absorbent polymer,
W 7 (g) is the total sum of the weight of the super absorbent polymer and the weight of the device capable of providing a load to the super absorbent polymer, and
W 8 (g) is the total sum of the weight of the super absorbent polymer and the weight of the device capable of providing a load to the super absorbent polymer, after absorbing a physiological saline solution to the super absorbent polymer under a load (0.3 psi) for 5 minutes and removing the remaining liquid with a vacuum device.

2. A super absorbent polymer comprising:
a base polymer powder containing a first crosslinked polymer of a water-soluble ethylene-based unsaturated monomer having an acidic group in which at least a part thereof is neutralized; and
a surface-crosslinked layer containing a second crosslinked polymer formed on the base polymer powder in which the first crosslinked polymer is additionally crosslinked via a surface crosslinking agent,
wherein the first crosslinked polymer is a porous polymer containing a plurality of pores on a micron (μm) scale,
wherein the superabsorbent polymer is prepared by:

1) performing thermal polymerization or photopolymerization of a monomer composition comprising the water-soluble ethylene-based unsaturated monomer having the acidic group in which at least the part thereof is neutralized, a carbonate forming agent, an anionic surfactant and a polymerization initiator to form a hydrogel polymer, wherein the anionic surfactant is dioctyl sodium sulfosuccinate,
2) drying the hydrogel polymer,
3) pulverizing the dried polymer, and
4) performing surface cros slinking reaction of the pulverized polymer;
wherein the super absorbent polymer has an average particle size of 300 μm to 600 μm, CRC of 28 g/g to 35 g/g, AUL (0.9 psi) of 18 g/g to 25 g/g, 5-min Gel-Vacuum AUL of 18 g/g to 25 g/g, and a vortex time of 5 seconds to 50 seconds,
wherein
the WAUL is measured according to the following Equation 1:
WAUL(g/g)=[W 2 (g)−W 1 (g)]/ W 0 (g)   [Equation 1]

in Equation 1,
W 0 (g) is an initial weight(g) of the super absorbent polymer,
W 1 (g) is the total sum of a weight of the super absorbent polymer and a weight of the device capable of providing a load to the super absorbent polymer,
W 2 (g) is the total sum of a weight of the super absorbent polymer and a weight of the device capable of providing a load to the super absorbent polymer, after absorbing a physiological saline solution below 15 cm from the super absorbent polymer under a load (0.7 psi) for 10 minutes,
wherein the vortex time means the amount of time required until the vortex disappears after adding 2 g of a super absorbent polymer to 50 mL of physiological saline solution and then stirring the mixture at 600 rpm,
wherein
the 5-min Gel-Vacuum AUL is measured according to the following Equation 5:
5-min Gel-Vacuum AUL(g/g)=[W 8 (g)−W 7 (g)]/ W 0 (g)   [Equation 5]

in Equation 5,
W 0 (g) is an initial weight(g) of the super absorbent polymer,
W 7 (g) is the total sum of the weight of the super absorbent polymer and the weight of the device capable of providing a load to the super absorbent polymer, and
W 8 (g) is the total sum of the weight of the super absorbent polymer and the weight of the device capable of providing a load to the super absorbent polymer, after absorbing a physiological saline solution to the super absorbent polymer under a load (0.3 psi) for 5 minutes and removing the remaining liquid with a vacuum device.

3. The super absorbent polymer according to claim 1 ,
wherein the super absorbent polymer has a rewetting amount of 0.05 g/g to 1 g/g, which is measured according to the following Equation 6:
Rewetting Amount (g/g)=[W 10 (g)−W 9 (g)]/W 0 (g)   [Equation 6]

in Equation 6,
W 0 (g) is an initial weight(g) of the super absorbent polymer,
W 9 (g) is an initial weight(g) of the second filter paper,
W 10 (g) is a weight(g) of the second filter paper that has absorbed a liquid leaking out from the super absorbent polymer swelled for 2 minutes under a load (0.7 psi), after the super absorbent polymers have absorbed 25 times their weight in a physiological saline solution for a sufficient time under no load condition.

4. A method of preparing a super absorbent polymer according to claim 1 :
1) performing thermal polymerization or photopolymerization of a monomer composition comprising a water-soluble ethylene-based unsaturated monomer having an acidic group in which at least a part thereof is neutralized, a carbonate forming agent, an anionic surfactant and a polymerization initiator to form a hydrogel polymer, wherein the anionic surfactant is dioctyl sodium sulfosuccinate,
2) drying the hydrogel polymer,
3) pulverizing the dried polymer, and
4) performing surface cros slinking reaction of the pulverized polymer.

5. The method of preparing a super absorbent polymer according to claim 4 ,
wherein the carbonate foaming agent is at least one selected from the group consisting of sodium carbonate, sodium hydrogen carbonate, magnesium carbonate, calcium carbonate, potassium carbonate, and potassium hydrogen carbonate.

6. The method of preparing a super absorbent polymer according to claim 4 ,
wherein the ca

Assignees

• Lg Chemical Ltd

Inventors

• Lee Sang Gi
• Nam Hye Mi
• Hwang Min Ho
• Lee Soo Jin
• Jang Tae Hwan

Classifications

• C08F2/10

  Aqueous solvent · CPC title

• C08F2/26

  anionic · CPC title

• C08K5/20

  Carboxylic acid amides · CPC title

• C08J3/075

  Macromolecular gels · CPC title

• C08F20/18 Primary

  with acrylic or methacrylic acids · CPC title