Barrier film with enhanced formability and a method for making thereof

A coextruded biaxially-oriented barrier film, comprising,

• (i) at least one outer heat sealable layer, comprising a (co)polyolefin with a Vicat softening temperature not exceeding 130° C.,
• (ii) at least one heat resistant layer, comprising at least one polar (co)polymer selected from the group consisting of (co)polyamides and aromatic (co)polyesters, and
• (iii) at least one core adhesive layer made of a material capable of adhering to both (co)polyolefins and polar (co)polymers,
• wherein
• a. said heat resistant layer, if it consists essentially of (co)polyamides, comprises not less than 15% of at least one copolyamide with a melting temperature not above 205° C.;
• b. a shrinkage value of the film in each a machine direction and a transverse direction after immersion for 10 seconds in water at a temperature of 90° C. is less than 10%;
• c. a shrinkage value of the film in at least one of the machine direction and the transverse direction is less than 3% after dwelling for 10 seconds in a drying cabinet preheated to 100° C.;
• and
• d. the film is capable of being thermoformed substantially free of ruptures, and the ratio between a mean thickness in unstrained film areas and a mean minimum thickness of the film in a resulting formed product is not more than 4.5, when vacuum thermoforming is carried out automatically by a thermoforming machine at a preset temperature of 100° C., a heating time of 3 s, a forming time of 2.5 s and a vacuum system pressure of 2 mm Hg by means of a forming die with four molding cavities in the form of rectangular parallelepipeds, each with the overall dimensions of 147×143×50 mm and rounding edges with a radius of 20 mm, assembled in a rectangular block with 18 mm gaps between the molding cavities in the machine direction and 15 mm gaps in the transverse direction.