Disposable diapers with main channels and secondary channels

1. A disposable diaper having a backsheet, a topsheet and an absorbent core disposed therebetween, and an acquisition layer disposed between the absorbent core and topsheet, wherein the absorbent core comprises at least one absorbent structure comprising a substrate layer and an absorbent layer comprising absorbent material, the absorbent layer comprising:

i. a width, N, extending in a transverse dimension and a length, M, extending in a longitudinal dimension;

ii. front, crotch and back regions arranged sequentially in the longitudinal dimension; and

iii. two longitudinal portions delimited by a central longitudinal axis of the absorbent structure;

wherein the absorbent layer comprises at least two main channels substantially free of the absorbent material extending through the thickness of the absorbent layer and at least present in the crotch region; and at least two secondary channels substantially free of the absorbent material extending through the thickness of the absorbent layer, and wherein the secondary channels are shorter than the main channels;

wherein the absorbent layer does not comprise channels substantially free of absorbent polymer particles extending up to longitudinal or transverse edges of the absorbent layer; and

the disposable diaper further comprising a second absorbent structure having a second substrate layer and a second absorbent layer comprising absorbent material and channels substantially free of the absorbent material extending through the thickness of the second absorbent layer, wherein the absorbent layer and the second absorbent layer are mirror images of each other and are combined in a laminate such that the channels of the second absorbent layer superpose the channels of the absorbent layer to form channels through the thickness of the laminate.

2. The disposable diaper of claim 1 , wherein the main channels extend for a length, L, wherein L is up to 90% of the length of M.

3. The disposable diaper of claim 1 , wherein the secondary channels have a length, V′, that is up to 45% of M.

4. The disposable diaper of claim 3 , wherein V′ is up to 30% of M.

5. The disposable diaper of claim 1 , wherein the main channels are straight.

6. The disposable diaper of claim 1 , wherein the secondary channels are straight.

7. The disposable diaper of claim 1 , wherein the main channels and/or the secondary channels have a percentage integrity of at least 20% according to the Wet Channel Integrity Test as detailed herein.

8. The disposable diaper of claim 1 , wherein two of the at least two main channels are mirror images of each other with respect to the central longitudinal axis.

9. The disposable diaper of claim 1 , wherein two of the at least two secondary channels are mirror images of each other with respect to the central longitudinal axis.

10. The disposable diaper of claim 1 , wherein the absorbent layer comprises cellulose.

11. The disposable diaper of claim 1 , wherein each of the main and/or secondary channels have a width of at least 3 mm.

12. The disposable diaper of claim 1 , wherein a majority of at least one of the secondary channels is disposed in the front region.

13. The disposable diaper of claim 1 , wherein a majority of at least one of the secondary channels is disposed in the back region.

14. The disposable diaper of claim 1 , wherein the main channels are curvilinear.

15. The disposable diaper of claim 1 , wherein at least one secondary channel is oblique or angled with respect to the central longitudinal axis.

16. The disposable diaper of claim 1 , wherein at least one of the main channels is oblique or angled with respect to the central longitudinal axis.

17. The disposable diaper of claim 1 , wherein at least one secondary channel extends in the transverse dimension.

18. The disposable diaper of claim 1 , wherein at least one main channel extends in the longitudinal dimension.

19. The disposable diaper of claim 1 , wherein at least one second channel extends in the longitudinal dimension.