Absorbent article

1. An absorbent article comprising:

a liquid absorbent layer for absorption and retention of liquid; and

a liquid passage layer located on a liquid-receiving side of the liquid absorbent layer, the liquid passage layer including:

a first passage layer; and

a second passage layer disposed between the first passage layer and the liquid absorbent layer, the first passage layer and the second passage layer being resin films formed with a plurality of liquid passage apertures,

each liquid passage aperture being defined by a peripheral wall projecting toward the liquid absorbent layer to provide the first passage layer and the second passage layer with thicknesses greater than a thickness of the resin film itself, the thickness of the first passage layer being the height of the peripheral wall in the first passage layer and the thickness of the second passage layer being the height of the peripheral wall in the second passage layer, and

wherein under a load in a thickness direction, the second passage layer has a greater thickness variation than the first passage layer and

wherein a percent open area for the second passage layer is greater than a percent open area for the first passage layer, where percent open area is determined as the ratio of a surface area open to the plurality of liquid passage apertures in the passage layer to a total surface area for the passage layer;

wherein material forming the resin film of the second passage layer is softer than the material forming the resin film of the first passage layer and

wherein the first passage layer is made of HDPE or MDPE and the second passage layer is made of LLDPE or LDPE.

2. The sanitary napkin of claim 1 , wherein when the individual first and second passage layers are under a load in a thickness direction, the second passage layer has a greater compression workload than the first passage layer.

3. The sanitary napkin of claim 2 , wherein the first passage layer has a compression workload equal to or greater than 0.1 Nm/m 2 .

4. The sanitary napkin of claim 2 , wherein the thickness of the second passage layer is greater than the thickness of the first passage layer.

5. The sanitary napkin of claim 1 , wherein when the individual first and second passage layers are under a load in a thickness direction, the second passage layer has a greater reduction in the open area of the liquid passage aperture than the first passage layer.

6. The sanitary napkin of claim 1 , wherein the thickness of the resin film forming the first passage layer is greater than the thickness of the resin film forming the second passage layer.

7. The sanitary napkin of claim 1 , wherein liquid passage apertures in the second passage layer each have a peripheral wall that is narrowed to reach a smallest sectional area midway in the thickness direction.

8. The sanitary napkin of claim 1 , wherein liquid passage apertures in the second passage layer each have a peripheral wall that is gradually narrowed in the thickness direction along an aperture axis that is directed obliquely to the thickness direction of the second passage layer.

9. The sanitary napkin of claim 8 , wherein each liquid passage aperture is bifurcated, having first and second peripheral walls gradually narrowed in the thickness direction respectively along first and second aperture axes directed obliquely to the thickness direction of the second passage layer.

10. The sanitary napkin of claim 1 , wherein liquid passage apertures in the second passage layer are each formed with a peripheral wall that is gradually narrowed in the thickness direction of the second passage layer and that has a plurality of cuts also extending in the thickness direction.

11. The sanitary napkin of claim 1 , wherein under a load in a thickness direction, the height of the peripheral wall in the second passage layer decreases at a rate greater than a rate of decrease of the height of the peripheral wall in the first passage layer.

12. The sanitary napkin of claim 11 , wherein under a predetermined load applied in a thickness direction, the second passage layer has a greater compressibility than the first passage layer and the peripheral wall in the first passage layer is more resistant to crushing as compared to the peripheral wall in the second passage layer.