B32B 3/30

Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form ; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids {; characterised by an apertured layer} characterised by a layer formed with recesses or projections, e.g. {hollows, grooves, protuberances, ribs }