Absorbent structures comprising coated super-absorbent polymer particles

• US 7,311,968 B2
• Filed: 06/26/2006
• Issued: 12/25/2007
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Ehrnsperger, Bruno Johannes, Opper, Heike, Schoenborn, Udo Friedel
• Primary Examiner(s): LE, HOA T
• Application Number:
  US11/474,857
• Publication Number:
  US 20060240229A1
• Time in Patent Office: 547 Days
• Field of Search: 428/327, 428/407
• US Class Current: 428/327
• CPC Class Codes: A61F 13/53 characterised by the absorbing medium A61F13/20 takes precedence
• CPC Class Codes: A61F 13/539 characterised by the connection of the absorbent layers with each other or with the outer layers
• CPC Class Codes: A61F 2013/53051 being only in particular parts or specially arranged
• CPC Class Codes: A61F 2013/530554 and being fixed to a web
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/254 Polymeric or resinous material
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2927 including structurally defined particulate matter
• CPC Class Codes: Y10T 442/699 Including particulate material other than strand or fiber material

Abstract

This invention is directed to super-absorbent material, which comprises a super absorbent polymer core that is coated with an organic, polar coating agent, and whereby the particulate super-absorbent material has a contact angle and a corresponding cos CA_m (as defined herein), whereby the cos CA_m is more than 0.3, and whereby, when said coating agent is in the form of particles, said coating agent particles have a (weight) mean particle size of from 0.001 to 1 micron. The material is useful for absorbent structures and absorbent articles (comprising such structures). The coated super-absorbent material is typically present in said absorbent structure at least at a concentration of 50% by weight of the structure, preferably even 80% or even 90%. The invention also provides a process for making the absorbent material.

Claims

1. An absorbent article comprising an absorbent structure, the absorbent structure comprising a particulate super-absorbent material, the super-absorbent material comprising a plurality of particulate cores, the particulate cores comprising super-absorbent polymers, wherein a plurality of the particulate cores are coated with a coating agent, the coating agent comprising an organic coating compound comprising one or more polar groups, and wherein the particulate super-absorbent material has a contact angle and a corresponding cos CA_m, wherein the cos CA_m is greater than 0.3, wherein the coating agent is in the form of particles, wherein the coating agent particles have a mean particle size from about 0.001 microns to about 1 micron, and wherein the coated particulate cores reduce surface tension of water by less than about 10%.

2. The absorbent article of claim 1 wherein the absorbent structure further comprises cellulose fibers.

3. The absorbent article of claim 1 wherein the absorbent article is selected from the group consisting of a sanitary napkin, a panty liner, a diaper, a training pant, and an adult incontinence article.

4. The absorbent article of claim 1 wherein the absorbent structure comprises at least a first area and a second area, wherein each of the first and second areas comprise the super-absorbent material, wherein the super-absorbent material within the first area is different from the super-absorbent material in the second area.

5. The absorbent article of claim 1, wherein the plurality of coated particulate cores have a surface area of at least about 0.01 m² gram.

6. The absorbent article of claim 5, wherein the plurality of particulate cores have a mean particle size from about 45 to about 850 microns.

7. The absorbent article of claim 6, wherein the organic coating compound makes up at least about 85% by weight of the coating agent.

8. The absorbent article of claim 5, wherein the plurality of particulate cores have a mean particle size from about 250 to about 450 microns.

9. The absorbent article of claim 1, wherein the plurality of coated particulate cores have a surface area of at least about 0.25 m² gram.

10. The absorbent article of claim 1, wherein the organic coating compound makes up at least about 60% by weight of the coating agent.

11. The absorbent article of claim 1, wherein the coating agent coats the particulate cores in a substantially permanent manner.

12. The absorbent article of claim 1, wherein the coating agent reduces a surface tension of the super-absorbent material by less than about 5%.

13. The absorbent article of claim 1, wherein the coating agent generally does nor reduce a surface tension of the super-absorbent material.

14. The absorbent article of claim 1, wherein none of the coating agent particles are more than about 50 microns.

15. The absorbent article of claim 1, wherein one or more of the polar groups have a molecular weight less than about 500 mol.

16. The absorbent article of claim 15, wherein the coating agent comprises at least one cationic polar group and at least one anionic polar group.

17. The absorbent article of claim 1, wherein the coating agent is applied to the plurality of particulate cores via dry mixing.

18. The absorbent article of claim 17, wherein the coating agent is mixed with the plurality of particulate cores for at least about 30 minutes.

19. The absorbent article of claim 1, wherein the coating agent compounds selected from the group consisting of N-(2-Acetamido)-2-aminoethansulfonic-acid, N-(2-Acetamido)-imino-di-acetic-acid, N-acetyl-glycin, β

-Alanine, Aluminum-hydroxy-acetate, N-Amidino-glycine, 2-Amino-ethyl-hydrogenphosphate, 2-Amino-ethyl-hydrogensulfate, Amino-methan-sulfonic-acid, Maleinic-acid, Arginine, Asparaginic-acid, Butane-di-acid, Bis(1-aminoguanidinium)-sulfate, 2-Oxo-propionic-acid, Tri-Calcium-di-citrate, Calciumgluconate, Calcium-saccharate, Calcium-Titriplex®

, Carnitine, Cellobiose, Citrulline, Creatine, Dimethylaminoacetic acid, Than-1,2-disulfonic-acid, Ethylendiammoniumsulfate, Fructose, Fumaric-acid, Galactose, Glucosamine, Gluconic-acid, Glutamine, 2-Amino-glutaric-acid, Glutaric-acid, Glycine, Glycylglycine, Imino-di-acetic-acid, Magnesium-glycerophosphate, Oxalicacid, Tetrahydroxy-adipinic-acid, Taurine, N-Methyl-taurin, Tris-(hydroxymethyl)-aminomethane, and N-(Tris-(hydroxymethyl)-methyl)-2-aminoethansulfonicacid.

20. The absorbent article of claim 1, wherein the organic coating compound further comprises an oxygen atom bound to a hydrogen atom.

21. The absorbent article of claim 1, wherein the organic coating compound is an organic derivates of an oxo acid, or salt or ester thereof.

22. The absorbent article of claim 1, wherein the organic coating compound has from 2 to 9 carbon atoms.