Wound dressing

1. A wound dressing comprising at least three layers including a first layer, a second layer and a third layer in order from a side used in contact with a wound site, the layers being integrally stacked together,

the first layer comprising a resin sheet material having a plurality of pores penetrating in a thickness direction,

wherein the thickness of the resin sheet material is 100 to 2000 μm,

wherein an opening of each pore on a surface used in contact with a wound site is 280 to 1400 μm in equivalent diameter,

wherein an opening of each pore on an opposite surface of the first layer is smaller than that on the surface used in contact with a wound site,

wherein the density of said pores is 50 to 400/cm 2 ,

wherein said surface used in contact with a wound site is hydrophobic,

wherein said first layer has an initial water pressure resistance, and

wherein the resin sheet material substantially does not allow water to permeate through any part other than said pores,

the second layer comprising a sheet material having a water-repellent surface, said second layer has an initial water pressure resistance higher than that of the first layer, and

the third layer comprising a sheet material capable of absorbing and holding water.

2. The wound dressing according to claim 1 further comprising a fourth layer comprising a resin film, a fabric or a nonwoven, in addition to the first layer, the second layer and the third layer, the layers being integrally stacked together.

3. The wound dressing according to claim 2 , wherein

the areas of the first to the third layers are the same,

the area of the fourth layer, which covers the first to the third layers, is larger than each area of the first to the third layers,

the fourth layer has an adhesive layer on at least a part of a non-stacked surface on the side having the stacked first to the third layers, and

at least a part around the periphery of the first to the third layers does not have the adhesive layer or the fourth layer.

4. The wound dressing according to claim 2 , wherein

the areas of the first to the third layers are the same,

the area of the fourth layer, which covers the first to the third layers, is larger than each area of the first to the third layers,

the fourth layer has an adhesive layer on at least a part of a non-stacked surface on the side having the stacked first to the third layers, and

the fourth layer has a slit or a small pore along at least a part of the periphery of the first to the third layers.

5. The wound dressing according to claim 1 , wherein the sheet material of the first layer is a polyolefin resin.

6. The wound dressing according to claim 1 , wherein

the sheet material of the second layer is a polyolefin resin,

the air permeability measured according to JIS-L-1096 is 5 to 2000 cm 3 /cm 2 ·s, and

the water repellency measured according to JIS-L-1092 is grade 3 or higher.

7. The wound dressing according to claim 1 , wherein the sheet material of the third layer is an airlaid nonwoven.

8. The wound dressing according to claim 1 , wherein the capacity of the retaining space between the wound site and the second layer is 0.015 to 0.55 μL per penetration pore.

9. A method for manufacturing the wound dressing according to claim 1 , comprising the step of applying a hot-melt adhesive to the sheet material of the second layer, wherein the hot-melt adhesive covers a portion but not all of the water-repellent surface of the sheet material of the second layer, followed by stacking the first layer sheet material onto the water-repellent surface of the sheet material of the second layer to join both layers.