a multi - layer sheet suitable as sealable or peelable sheet specially used for closing foodstuff containers or blisters . this multi - layer sheet comprises a tie - layer between a substrate layer and a seal or a peel - seal layer comprising a polyolefin with acid or anhydride , grafted or copolymerized . the tie - layer has a thickness equivalent to 1 - 7 g / m 2 . the seal layer comprises a polyolefin . the total thickness of the combination of tie - layer and seal layer is equivalent to 3 - 20 g / m . this multilayer sheet is prepared by extrusion or coextrusion coating .