Absorbent structure with improved water-absorbing material

• US 20080027402A1
• Filed: 08/03/2007
• Published: 01/31/2008
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Axel Meyer, Jean-Philippe Autran, Karl Haeberle, Mark Elliott, Matthias Schmidt, Renae Fossum, Stefan Bruhns, Thomas Daniel, Ulrich Riegel
• Original Assignee: Axel Meyer, Jean-Philippe Autran, Karl Haeberle, Mark Elliott, Matthias Schmidt, Renae Fossum, Stefan Bruhns, Thomas Daniel, Ulrich Riegel
• Inventors: Autran, Jean-Philippe, Schmidt, Mattias, Riegel, Ulrich, Daniel, Thomas, Elliott, Mark, Meyer, Axel, Bruhns, Stefan, Haeberle, Karl, Fossum, Renae
• Granted Patent: US 8,287,999 B2
• Time in Patent Office: Days
• US Class Current: 604/368
• CPC Class Codes: A61L 15/26 Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 15/50 Lubricants; Anti-adhesive agents
• CPC Class Codes: C08L 75/04 Polyurethanes
• CPC Class Codes: Y10T 428/254 Polymeric or resinous material
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer
• CPC Class Codes: Y10T 442/60 Nonwoven fabric [i.e., nonwoven strand or fiber material]

Abstract

The present invention relates to an absorbent structure suitable in, or being an adult or infant diaper or feminine hygiene article, comprising a water-absorbing material comprising water-absorbing particles that comprise a film coating, comprising an elastic film-forming polymer and an antioxidant. The invention also relates to an absorbent structure comprising a water absorbent material obtainable by a process of: a) spray-coating water-absorbing polymeric particles with an elastic film-forming polymer in a fluidized bed reactor at a temperature in the range from 0° C. to 150° C. and b) heat-treatment of the coated polymeric particles at a temperature above 50° C., wherein in step a) and/or b) an antioxidant is added.

Claims

1. An absorbent structure for use in an adult or infant diapers or feminine hygiene articles, the absorbent structure comprising a water-absorbing material, the water-absorbing material comprising water-absorbing particles, wherein the water absorbent particles comprise a film coating, and wherein the film coating comprises an elastic film-forming polymer and an antioxidant.

2. The absorbent structure of claim 1, wherein the film coating is a heat-treated or annealed film coating.

3. The absorbent structure of claim 1, wherein the water-absorbing particles are post-crosslinked.

4. The absorbent structure of claim 1, wherein the elastic film-forming polymer is a polyurethane.

5. The absorbent structure of claim 1, wherein the elastic film-forming polymer is a polyurethane dispersion blended with at least one polymer dispersion selected from the group consisting of poly-co(ethylene-vinylacetate), polyacetale and homo- and copolymers of acrylonitrile, butadiene, styrene, (meth-)acrylate, isoprene, and vinylpyrrolidone.

6. The absorbent structure of claim 1, wherein the antioxidant comprises a hindered phenol, secondary aromatic amine, certain sulfide ester, trivalent phosphorus compound, hindered amine, metal dithiocarbamate, a metal dithiophosphate, or mixture(s) thereof.

7. The absorbent structure of claim 1, wherein the antioxidant comprises one or more alkylated monophenols, hydroquinones, alkylated hydroquinones, tocopherol and its derivatives, chromanol and its derivatives, ascorbic acid, and Irganox 1010.

8. The absorbent structure of claim 1, wherein the film-coating comprises a coalescing agent and/or a deagglomerating aid.

9. The absorbent structure of claim 1, wherein the film coating is homogeneous.

10. The disposable absorbent structure of claim 1, comprising an absorbent core that comprises the water-absorbing material and less than 20% by weight (of the water-absorbing material) of fibrous absorbent material, the core being substantially free of absorbent fibrous material.

11. The disposable absorbent structure of claim 10, wherein the absorbent core comprises (fibrous) adhesive or thermoplastic material.

12. The disposable absorbent structure of claim 1, wherein the water-absorbing material has a CCRC and CRC of not less than 25 g/g, and/or a CS-SFC of at least 350×

10<sup>−

7</sup> cm³s/g.

13. An absorbent structure comprising a water absorbent material obtainable by a process of:

a) spray-coating water-absorbing polymeric particles with an elastic film-forming polymer in a fluidized bed reactor at a temperature in the range from 0°

C. to 150°

C.;

b) heat-treatment of the coated polymeric particles at a temperature above 50°

C.; and

wherein in step a) and/or b) an antioxidant is added.

14. The absorbent structure of claim 13, wherein the heat-treatment of step b) is carried out at a temperature in the range from 100°

to 200°

C., and wherein the duration of the heat-treatment is chosen that the CS-SFC value of the obtained polymeric particles is at least 10% of the optimum CS-SFC value.

15. The absorbent structure of claim 13, wherein the water-absorbing polymeric particles are post-crosslinked.

16. The absorbent structure of claim 13, wherein the elastic film-forming polymer is a polyurethane.

17. The absorbent structure of claim 16, wherein the elastic film-forming polymer is a polyurethane dispersion blended with at least one polymer dispersion selected from the group consisting of poly-co(ethylene-vinylacetate), polyacetale and homo- and copolymers of acrylonitrile, butadiene, styrene, (meth-)acrylate, isoprene, and vinylpyrrolidone.

18. The absorbent structure of claim 13, wherein the antioxidant comprises a hindered phenol, secondary aromatic amine, certain sulfide ester, trivalent phosphorus compound, hindered amine, metal dithiocarbamate, metal dithiophosphate, or mixture(s) thereof.

19. The absorbent structure of claim 18, wherein the antioxidant comprises one or more alkylated monophenols, hydroquinones, alkylated hydroquinones, tocopherol and its derivatives, chromanol and its derivatives, ascorbic acid, and Irganox 1010.

20. The absorbent structure of claim 13, wherein the heat-treatment of step b) is carried out at a temperature in the range from 100°

to 200°

C., and wherein the duration of the heat-treatment is chosen that the CS-SFC value of the obtained polymeric particles is at least 10% of the optimum CS-SFC value.