Absorbent core with profiled distribution of absorbent material
An absorbent core for absorbent articles such as diapers comprising a core wrap comprising a top side and a bottom side, an absorbent material between the top side and the bottom side of the core wrap, a first and second longitudinally-extending channel-forming areas disposed on opposite sides of the longitudinal axis and substantially free of absorbent material preferably through which the top side of the core wrap is preferably attached to the bottom side of the core wrap. The core has a central absorbent zone between the first and the second channel-forming areas and a first and second lateral absorbent zones disposed laterally outwardly. The basis weight of the absorbent material in the central absorbent zone is higher than the basis weight of the absorbent material in each of the lateral absorbent zones for at least a first transversal section (S 1 ). This relation is inverted along a second transversal section (S 2 ) of the core. The first and second sections have each a length in the longitudinal direction of at least 10 mm.
1. An absorbent core extending in a longitudinal direction parallel to a longitudinal axis from a length L and a transversal direction perpendicular to the longitudinal direction, wherein the absorbent core comprises:
a front edge and a back edge;
a core wrap comprising a top side and a bottom side;
an absorbent material between the top side and the bottom side of the core wrap;
a first and second longitudinally-extending channel-forming areas substantially free of absorbent material and each having a length, and wherein the first channel-forming area is on one side of the longitudinal axis and the second channel-forming area is on another side of the longitudinal axis;
a central absorbent zone comprising absorbent material and disposed between the first and the second channel-forming areas; and
a first lateral absorbent zone and a second lateral absorbent zone comprising absorbent material and disposed laterally outwardly of and extending along the length of the first channel-forming area and the second channel-forming area respectively; and
a transversal axis disposed a distance of 0.45 L from the front edge;
a crotch region extending from the transversal axis towards the back edge and front edge of the core by a distance of a quarter of L (L/4) in both directions for a total length of L/2;
wherein:
a basis weight of the absorbent material in the central absorbent zone is higher than a basis weight of the absorbent material in each of the lateral absorbent zones for at least a first transversal section (S 1 ) of the core having a first length in the longitudinal direction of at least 10 mm and a first width in the lateral direction that extends across the first lateral absorbent zone, the central absorbent zone, and the second lateral absorbent zone; and
the basis weight of the absorbent material in the central absorbent zone is lower than the basis weight of the absorbent material in each of the lateral absorbent zones for at least a second transversal section (S 2 ) of the core, wherein the second transversal section (S 2 ) is adjacent to the first transversal section (S 1 ) and has a second length in the longitudinal direction of at least 10 mm and a first width in the lateral direction that extends across the first lateral absorbent zone, the central absorbent zone, and the second lateral absorbent zone; and
wherein the basis weight of the first lateral absorbent zone in the first transversal section (S 1 ) is less than the basis weight of the first lateral absorbent zone in the second transversal zone, and the basis weight of the central absorbent zone is greater in the first transversal zone (S 1 ) than in the second transversal section (S 2 ) and
wherein at least one transversal folding line is formed in a transversal section (S 4 ) of the core in the crotch region and having a minimum basis weight in the lateral absorbent zones relative to the neighboring regions of the lateral absorbent zones, so that the transversal section (S 4 ) of minimum basis weight acts as a folding line and wherein the transversal section (S 4 ) comprises a longitudinal length of 5 mm to 30 mm.
2. The absorbent core of claim 1 , wherein the basis weight of the absorbent material in the central absorbent zone is about equal to the basis weight of the absorbent material in the lateral absorbent zones along a third transversal sections (S 3 ) of the core having a length of at least 10 mm in the longitudinal direction.
3. The absorbent core of claim 1 , wherein:
the basis weight difference between a maximum basis weight value in the central absorbent zone and a minimum basis weight value in any of the lateral absorbent zones in the first transversal section (S 1 ) is of at least 20 g/m 2 ; and
the basis weight difference between a maximum basis weight value in any of the lateral absorbent zones and a minimum basis weight value in the central absorbent zone in the second transversal section (S 2 ) is of at least 10 g/m 2 .
4. The absorbent core of claim 3 , wherein the basis weight difference between the maximum basis weight value in the central absorbent zone and the minimum basis weight value in any of the lateral absorbent zones in the first transversal section (S 1 ) is of at least 50 g/m 2 .
5. The absorbent core of claim 3 , wherein the basis weight difference between the maximum basis weight value in any of the lateral absorbent zones and the minimum basis weight value in the central absorbent zone in the second transversal section (S 2 ) is of at least 30 g/m 2 .
6. The absorbent core of claim 1 , wherein the first and second channel-forming areas are at least partially curved or angled so that the width of the central absorbent zone varies along at least a portion of the length of the core.
7. The absorbent core of claim 1 , wherein the amount of absorbent material in the central absorbent zone ranges from about 15% to about 55% of the total amount of absorbent material in the absorbent core, and the combined amount of absorbent material in both lateral absorbent zones ranges from about 20% to about 80% of the total amount of absorbent material in the absorbent core.
8. The absorbent core of claim 1 , wherein a minimum width (D) of the central absorbent zone is at least 10 mm.
9. The absorbent core of claim 1 , wherein the top side of the core wrap is attached to the bottom side of the core wrap in the first and second channel-forming areas.
10. The absorbent core of claim 1 , wherein the absorbent material consists essentially of superabsorbent polymer particles.
11. The absorbent core of claim 10 , wherein the superabsorbent polymer particles are at least partially immobilized by an adhesive.
12. The absorbent core of claim 1 , further comprising a front absorbent zone comprising absorbent material and disposed longitudinally outwardly of the central absorbent zone and the lateral absorbent zones towards the front edge of the core, and a back absorbent zone comprising absorbent material and disposed longitudinally outwardly of the central absorbent zone and the lateral absorbent zones towards the back edge of the core.
13. The absorbent core of claim 1 , comprising an auxiliary glue between the absorbent material and at least one of the top side or the bottom side of the core wrap.
14. The absorbent core of claim 1 , wherein the top side of the core wrap is attached to the bottom side of the core wrap in the channel-forming areas by at least one selected from ultrasonic bonding, fusion bonding, and adhesive bonding.