The subject of the present invention is a composite wound packing material comprising a casing enclosing a material, or an assembly of materials, forming fluid flow channels, said casing being composed of a self-supporting interface material formed from a thin layer of a composition comprising a hydrophobic matrix and comprising through-holes, said hydrophobic matrix comprising, per 100 parts by weight of a styrene/saturated olefin/styrene triblock copolymer having a viscosity of between 0.2 and 2 Pa·s, as measured in a 10% (weight/weight) solution in toluene, from 400 to 1220 parts by weight of a plasticizer, preferably a plasticizing oil, and from 0 to 720 parts by weight of petroleum jelly, it being specified, moreover, that the total amount of plasticizer and petroleum jelly is greater than or equal to 750 parts by weight and the amount of petroleum jelly is between 400 and 720 parts by weight when the amount of plasticizer is between 1000 and 1220 parts by weight.