FIELD: manufacturing process.
SUBSTANCE: invention relates to a barrier film used in food packaging in modified atmosphere. The barrier film consists of five superimposed layers. The barrier film includes a central barrier layer containing the first mixture of copolymer of ethylene and vinyl alcohol, constituting the bulk of the weight, and polyamide. The barrier film comprises two outer layers containing the second mixture of copolymers of ethylene and α-olefins. The barrier film comprises two adhesive layers between the central layer and two outer layers, respectively. The second mixture of copolymers of ethylene and α-olefins, at least in one of the outer layers contains only the first copolymer of ethylene and α-olefin having a density less than or equal to 0.925 g/cm3, and greater than or equal to 0.915 g/cm3, and the second metallocene copolymer of ethylene and α-olefin having a density less than or equal to 0.910 g/cm3. Fractions of the second polymer relative to the weight of its outer layer constitute a value greater than or equal to 20%, and less than or equal to 45%. The temperature of weld starting to obtain the breaking strength on the weld joint of greater than or equal to 15 N/30 mm, is lower than 120° C. The breaking strength on the weld joint of the film constitutes a value greater than or equal to 10 N/30 mm, after a stay in a water bath for one and a half hours at 85° C.
EFFECT: increased thermal stability of welded seams.
25 cl, 2 dwg, 4 tbl, 2 ex
