Laminate of thermoplastic film materials exhibiting throughgoing porosity

A laminate of thermoplastic film materials exhibiting throughgoing porosity and comprising:

• plies A and B,
• the ply A having an inner surface A1 partly in contact with the ply B and an outer surface A2, and
• the ply B having an inner surface B1 partly in contact with the ply A and an outer surface B2,
• where the ply A and the ply B comprise continuous material except for a multitude of perforations in each ply, whereby substantially no perforation in the ply A corresponds directly to a perforation in the ply B,
• where the lamination between the ply A and the ply B on surfaces A1 and B1 being:
• a) through a coextruded lower melting lamination layer on the ply A and/or the ply B and
• b) established in such a discontinuous manner that there is formed a channel system between the surfaces A1 and B1 connecting a majority of the perforations in the ply A each with at least one of the perforations in the ply B, and connecting a majority of the perforations in the ply B each with at least one of the perforations in the ply A, and
• characterized in that each channel includes a barrier part having a gap as measured from the surface A1 to the surface B1 limited to about 200 μm or less, where the gap being formed by surface irregularities in the surface A1 and/or the surface B1 and where the surface irregularities comprise protruding thicker bosses and thinner receding portions, where the channels and the barrier parts withstand hydrostatic pressure and dynamic water pressure, but allow passage of vapor and air.