Method of applying structural elements to an absorbent article

1. A method of applying structural elements to an absorbent article having a longitudinal direction and a transverse direction, side edges extending in the longitudinal direction and end edges extending in the transverse direction, said absorbent article comprising a top sheet and a back sheet, the method comprising:

applying expandable ink to the top sheet at at least a central area of the top sheet, and

activating the expandable ink to obtain three-dimensional structural elements on the top sheet, such that a height of the three-dimensional structural elements at the central area decreases in a direction from the center of the central area toward the side edges.

2. The method of claim 1 , wherein the expandable ink is applied on 1-50% of the surface area of the top sheet.

3. The method of claim 1 , wherein the expandable ink is activated by subjecting the top sheet to heat.

4. The method of claim 3 , wherein the heat is generated from one of infra-red radiation, hot air, microwaves, and a heated embossing roll.

5. The method of claim 1 , wherein the expandable ink is activated by UV radiation.

6. The method of claim 1 , wherein the expandable ink comprises a polymer, a solvent and a blowing agent or expandable microspheres.

7. The method of claim 1 , wherein the expandable ink is applied as one or more liquid barriers selected from: in a crotch region along at least a part of the longitudinal side edges; a transverse front of the absorbent article;

and a back region of the absorbent article.

8. The method of claim 7 , wherein the one or more liquid barriers are formed of continuous and/or dotted lines.

9. The method of claim 1 , wherein a cluster of dots of expandable ink is applied in a central longitudinal part of the absorbent article, forming a raised portion, and wherein a ratio between a height of the dots and a distance between the dots in the cluster is at least 1:1.

10. The method of claim 1 , wherein the expandable ink is applied along at least a part of a transverse end edge of the absorbent article.

11. The method of claim 1 , wherein a hydrophobic ink is applied along at least a part of at least one of a longitudinal side edge and a transverse end edge, and a hydrophilic ink is applied in a central and longitudinal part of the top sheet.

12. The method of claim 1 , wherein the top sheet has a first surface facing away from the back sheet, and a second surface facing towards the back sheet, and wherein the expandable ink is applied to one or both of said first and second surfaces.

13. The method of claim 1 , wherein the structural elements are applied on an absorbent article that is one of: a sanitary napkin; a panty liner; a male or female incontinence article; and a diaper.

14. An absorbent article comprising a top sheet provided with three-dimensional structural elements, wherein the three-dimensional structural elements consist of expandable ink that has been applied to the top sheet at at least a central area of the top sheet, and that has been subsequently activated at least partly to form the three-dimensional structural elements, such that a height of the three-dimensional structural elements at the central area decreases in a direction from the center of the central area toward side edges of the absorbent article.

15. The absorbent article of claim 14 , wherein the three-dimensional structural elements have a height of 0.1-15 mm.

16. The absorbent article of claim 14 , wherein 1-50% of the top sheet is covered with expandable ink.

17. A method of applying structural elements to an absorbent article having a longitudinal direction and a transverse direction, side edges extending in the longitudinal direction and end edges extending in the transverse direction, said absorbent article comprising a top sheet and a back sheet, the method comprising:

applying expandable ink to the top sheet, at least some of the expandable ink being hydrophilic, and

activating the expandable ink to obtain three-dimensional structural elements on the top sheet, wherein a cluster of dots of expandable ink is applied in a central longitudinal part of the absorbent article, forming a raised portion, and wherein a ratio between a height of the dots and a distance between the dots in the cluster is at least 1:1.