| 摘要 |
The invention relates to a process and a film in which the water vapour-sensitive barrier layers for gases are enclosed in the centre of the film and bonded by melting. The gas barrier layers consist optionally of an ethylene-vinyl alkanoate (ethylene-vinyl alcohol), known as EVAL or EVOH, and a polyamide, and the water vapour-tight sealing layers consist of a polyolefin, preferably a polyethylene. By virtue of the capability of hot bonding one of the layers disposed in the centre with the other layer disposed in the centre of the film, an inseparable bond is formed, so that the gas barrier layers are doubled in comparison to other film designs and are thus more reliable. Depending on its construction, the film has 7 to 9 layers and is highly efficient in comparison to 3-layer films or 5-layer films known hitherto.
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