A film composite for packaging purposes. The film composite efficiently
blocks the passage of water vapor and gas after sterilization in a water
bath or in water vapor at temperatures of more than 90.degree. C., and is
a film consisting of polyethylene terephthalate (PET) with a coextruded
layer consisting of polyethylene-2,6-naphthalate (PEN) on at least one
side. The film has a 10 nm to 200 nm thick ceramic layer on at least one
of the sides that are coated with PEN. The layer is produced by
simultaneously vaporizing silicon dioxide (SiO.sub.2) and metallic silicon
in a vacuum. The layer consists of SiO.sub.x, x being a number between 0.9
and 2. The composite film blocks the passage of water vapor and gases to a
large extent after sterilization in a water bath or in water vapor at
temperatures of more than 90.degree. C. A process for preparing the film
composite.
