| 摘要 |
A polyolefin packaging film of the kind that comprises an outer layer and an inner layer that both contain a thermoplastic polyolefin, and wherein the Tm of the inner layer is lower than the Tg of the outer layer, and wherein at least 50w% of the total polyolefin content of the outer layer is composed of at least one cycloolefin copolymer (COC), enabling high packaging rates and tightly-closing sealings on sealing of especially foodstuff packagings. The high Tg of the outer layer enables utilization of very high sealing temperatures without the film melting and adhering to the sealer bars and provides good stretch stability and cutting ability. Preferably the outer layer, or both the outer layer and the inner layer contain a cycloolefin copolymer and by means of different films inserted between the outer layer and the inner layer, the properties of the packaging film, such as e.g. tensile strength, oxygen barrier, water vapour barrier, thickness, and stretchability, can be designed for the desired purpose. The packaging film is co-extruded either by blown or flat sheet co-extrusion and is especially used for packing of foodstuff.
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