Patent ID: 7255902

Claim:
A multilayer barrier film comprising a filled layer based on polypropylene and a plurality of unfilled layers, wherein the filled layer is filled with 40-75 weight %, based on the total weight of the filled layer, of an inorganic filler, forms one of the two surface layers of the film, and has a thickness of 40 μm to 400 μm, the unfilled layers comprising at least a barrier layer and a sealing layer and optionally at least one adhesive layer, and the ratio of the total thickness of the unfilled layers to the thickness of the filled layer being from 1:8 to 1:1.2, wherein the sealing layer forms the other of the two surface layers of the film and the barrier layer is sandwiched between the filled layer and the sealing layer, and wherein the film is printed and laminated by adhesives after a corona, flame, fluorine or plasma pretreatment.