Absorbent article comprising a liquid-permeable material layer

1. An absorbent article comprising a liquid-permeable surface layer and a liquid-impermeable surface layer and an absorption body arranged between the surface layers, the absorption body comprising a liquid-permeable material layer and an absorbent structure, the absorbent structure having the ability to expand on wetting and having a first volume in a dry condition and a second volume in a completely expanded wet condition, the second volume being greater than the first volume,

wherein the liquid-permeable material layer constitutes a volume-limiting device for the absorbent structure so that the absorbent structure is prevented from reaching the completely expanded wet condition on wetting in an excess of 0.9% NaCl solution for 5 minutes and so that the absorbent structure after wetting in an excess of 0.9% NaCl solution for 5 minutes has a greater stiffness than in the dry condition and thus forms a forming element in the absorbent article, wherein the absorbent structure expands to a mean value of 70% or less of the completely expanded wet condition on wetting in an excess of 0.9% NaCl solution for 5 minutes, based on g/g increase.

2. The absorbent article in accordance with claim 1 , wherein the absorbent structure can expand when wetted to a maximum volume which is ⅔ of the second volume of the absorbent structure.

3. The absorbent article in accordance with claim 1 , wherein the absorbent structure comprises a polyacrylate-based foam material.

4. The absorbent article in accordance with claim 1 , wherein the absorbent structure comprises a mixture of superabsorbent materials and fibres.

5. The absorbent article in accordance with claim 4 , wherein the fibres comprise absorbent fibres.

6. The absorbent article in accordance with claim 5 , wherein the absorbent fibres comprise cellulose fluff pulp.

7. The absorbent article in accordance with claim 1 , wherein the liquid-permeable material layer comprises a nonwoven material.

8. The absorbent article in accordance with claim 1 , wherein the liquid-permeable material layer comprises a perforated plastic film.

9. The absorbent article in accordance with claim 1 , the absorbent article further comprising two longitudinal side edges, and the absorbent structure forms raised liquid barriers arranged along the longitudinal side edges.

10. The absorbent article in accordance with claim 1 , wherein the absorbent structure in the dry condition has a density that is at least 0.5 g/cm 3 .

11. The absorbent article in accordance with claim 1 , wherein the absorbent structure in the dry condition has a density that is at least 0.7 g/cm 3 .

12. The absorbent article in accordance with claim 1 , wherein the total absorption capacity per cubic centimeter of the absorbent structure in the dry condition is at least 15 g/cm 3 .

13. An absorbent article comprising a liquid-permeable surface layer and a liquid-impermeable surface layer and an absorption body arranged between the surface layers, the absorption body comprising a liquid-permeable material layer and an absorbent structure, the absorbent structure having the ability to expand on wetting and having a first volume in a dry condition and a second volume in a completely expanded wet condition, the second volume being greater than the first volume,

wherein the liquid-permeable material layer constitutes a volume-limiting device for the absorbent structure so that the absorbent structure is prevented from reaching the completely expanded wet condition on wetting in an excess of 0.9% NaCl solution for 5 minutes and so that the absorbent structure after wetting in an excess of 0.9% NaCl solution for 5 minutes has a greater stiffness than in the dry condition and thus forms a forming element in the absorbent article,

the absorbent article further comprising a thickness direction,

wherein the absorption body comprises an acquisition area for receiving body fluid, the acquisition area comprising at least a cavity or an area with a lower density than a part of the absorption body that is adjacent to the acquisition area and is situated chiefly in a single plane, and the part that is adjacent to the acquisition area comprises the absorbent structure, wherein the absorbent structure forms a raised barrier arranged on each side of the acquisition area in a longitudinal direction of the acquisition area, the absorbent structure chiefly increases in diameter in the thickness direction of the article during wetting and the size of the acquisition area increases in the thickness direction during wetting.