SUPER ABSORBENT POLYMER AND A PREPARATION METHOD THEREOF

• US 20150087742A1
• Filed: 04/23/2013
• Published: 03/26/2015
• Est. Priority Date: 04/25/2012
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Won, Tae-Young, Han, Chang-Sun, Kim, Gi-Cheul, Lee, Sang-Gi, Kim, Kyu-Pal, Leem, Gyu, Lee, Yong-Hun, Park, Sung-Soo
• Granted Patent: US 9,517,446 B2
• Time in Patent Office: Days
• US Class Current: 522/181
• CPC Class Codes: A61L 15/24 Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: B01J 20/267 Cross-linked polymers
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28016 Particle form
• CPC Class Codes: B01J 20/3085 Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
• CPC Class Codes: B01J 20/3208 Polymeric carriers, supports or substrates
• CPC Class Codes: B01J 20/3248 the functional group or the linking, spacer or anchoring group as a whole comprising at least one type of heteroatom selected from a nitrogen, oxygen or sulfur, these atoms not being part of the carrier as such
• CPC Class Codes: B01J 2220/68 Superabsorbents
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 222/102 of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate
• CPC Class Codes: C08J 2300/14 Water soluble or water swellable polymers, e.g. aqueous gels
• CPC Class Codes: C08J 2333/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08J 3/075 Macromolecular gels
• CPC Class Codes: C08J 3/12 Powdering or granulating
• CPC Class Codes: C08J 3/126 Polymer particles coated by polymer, e.g. core shell structures
• CPC Class Codes: C08J 3/24 Crosslinking, e.g. vulcanising, of macromolecules mechanical aspects B29C35/00; crosslinking agents C08K
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking

Abstract

The present invention relates to a super absorbent polymer (SAP) and a preparation method thereof. More specifically, the present invention provides a SAP satisfying the overall properties required to a SAP and especially the superior initial absorbency and absorbing rate under load at the same time, and a preparation method thereof, by treating the surface of the SAP with a surface treatment solution including water and a diol-based or glycol-based surface crosslinking agent.

Claims

1. A super absorbent polymer (SAP), having the SPAN value of 1.2 or less, represented by the following Mathematical Formula 1, and

satisfying the absorbing rate under load represented by the following Mathematical Formula 2:

SPAN=[D(90%)−

D(10%)]/D(50%)≦

1.2 

 

[Mathematical Formula 1]

in Mathematical Formula 1,

D(90%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 90%,

D(10%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 10%, and

D(50%) is the diameter of the particle when the accumulated weight from the smallest particle becomes 50%,

1.0>

ARUL=AUP(10 min)/AUP(60 min)>

0.70 

 

[Mathematical Formula 2]

in Mathematical Formula 2,

ARUL is the absorbing rate under load, AUP (10 min) is the absorbency under pressure after 10 mins represented by the following Mathematical Formula 3, and AUP (60 min) absorbency under pressure after 60 mins represented by the following Mathematical Formula 3,

AUP(g/g)=[Wb(g)−

Wa(g)]/weight of absorbent polymer(g) 

 

[Mathematical Formula 3]

in Mathematical Formula 3,

Wa (g) is the sum of the weight of the absorbent polymer and the weight of the device capable of providing load to the absorbent polymer, and

Wb (g) is the sum of the weight of the absorbent polymer in which moisture is absorbed under load (0.7 psi) for 1 hr and the weight of the device capable of providing load to the absorbent polymer.

2. The super absorbent polymer according to claim 1, including a crosslinked polymer obtained by crosslinking the surface of a powdery base polymer polymerized from at least partially neutralized water-soluble ethylenic unsaturated monomer including an acid group with a C₂-C₈ diol-based or glycol-based compound.

3. The super absorbent polymer according to claim 2, wherein the water-soluble ethylenic unsaturated monomer includes one or more monomers selected from the group consisting of:

anionic monomers of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloyl ethane sulfonic acid, 2-methacryloyl ethane sulfonic acid, 2-(meth)acryloyl propane sulfonic acid, and 2-(meth)acrylamide-2-methyl propane sulfonic acid, and salts thereof;

nonionic hydrophilic monomers of (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, methoxy polyethyleneglycol(meth)acrylate, and polyethyleneglycol (meth)acrylate; and

amino-containing unsaturated monomers of (N,N)-dimethylaminoethyl (meth)acrylate and (N,N)-dimethylaminopropyl (meth)acrylamide, and a quaternary compound thereof.

4. A method of preparing the super absorbent polymer of claim 1, including the steps of:

preparing a monomer composition including a water-soluble ethylenic unsaturated monomer and a polymerization initiator;

preparing a hydrogel polymer by polymerizing said monomer composition in a polymerization reactor;

drying and pulverizing said hydrogel polymer;

classifying said pulverized hydrogel polymer; and

treating the surface of said hydrogel polymer by spraying a surface treatment solution including water and a surface crosslinking agent on each of the classified hydrogel polymer particles.

5. The method according to claim 4, wherein the surface crosslinking agent is a C₂-C₈ diol-based or glycol-based compound.

6. The method according to claim 4, wherein the surface treatment solution further includes one or more organic solvents selected from the group consisting of ethanol, methanol, isopropylalcohol, ethyleneglycol, propyleneglycol, polyethyleneglycol, and polypropyleneglycol.

7. The method according to claim 4, wherein the concentration of the surface crosslinking agent in the surface treatment solution is 0.1 to 10 weight %.

8. The method according to claim 4, wherein the surface treatment solution is sprayed on the substrate on which the classified hydrogel polymer is spread, by controlling the angle of 1°

to 45°

from the hydraulic nozzle of the spraying device.

9. The method according to claim 4, wherein the step of treating the surface includes the steps of feeding the classified hydrogel polymer to a surface crosslinking reactor, and carrying out a surface crosslinking reaction of the hydrogel polymer at 120 to 250°

C. for 10 to 120 mins.

10. The method according to claim 4, wherein the step of drying and pulverizing the hydrogel polymer is carried out so that the particle size of the dried hydrogel polymer becomes 150 to 850 μ

m.

11. The method according to claim 4, wherein the classifying step includes the steps of:

classifying the pulverized hydrogel polymer into 2 grades of the particle size below 150 μ

m and the particle size of 150 μ

m to 850 μ

m;

classifying the pulverized hydrogel polymer into 3 grades of the particle size below 150 μ

m, the particle size of 150 μ

m or more and below 300 μ

m, and the particle size of 300 μ

m to 850 μ

m;

or

classifying the pulverized hydrogel polymer into 4 grades of the particle size below 150 μ

m, the particle size of 150 μ

m or more and below 300 μ

m, the particle size of 300 μ

m or more and below 600 μ

m, and the particle size of 600 μ

m to 850 μ

m.

12. The method according to claim 4, further including the step of pulverizing and classifying the hydrogel polymer into the particles having the particle size of 150 to 850 μ

m after the step of treating the surface of the hydrogel polymer.

13. The method according to claim 4, further including the step of pulverizing the hydrogel polymer to have the particle size of 1 mm to 15 mm after the polymerization and before the step of drying the hydrogel polymer.

14. The method according to claim 4, wherein the polymerization is carried out by a UV polymerization or a thermal polymerization.

15. The method according to claim 4, wherein the water-soluble ethylenic unsaturated monomer includes one or more monomers selected from the group consisting of:

anionic monomers of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, 2-acryloyl ethane sulfonic acid, 2-methacryloyl ethane sulfonic acid, 2-(meth)acryloyl propane sulfonic acid, and 2-(meth)acrylamide-2-methyl propane sulfonic acid, and salts thereof;

nonionic hydrophilic monomers of (meth)acrylamide, N-substituted (meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, methoxy polyethyleneglycol(meth)acrylate, and polyethyleneglycol (meth)acrylate; and

amino-containing unsaturated monomers of (N,N)-dimethylaminoethyl (meth)acrylate and (N,N)-dimethylaminopropyl (meth)acrylamide, and a quaternary compound thereof.

16. The method according to claim 4, wherein the polymerization initiator is any one compound selected from the group consisting of an azo-based initiator, a peroxide-based initiator, a redox-based initiator, an organic halide initiator, acetophenone, benzoin, benzophenone, benzyl, and a derivative thereof.

17. The method according to claim 4, wherein the monomer composition further includes a crosslinking agent.