Abstract: The invention concerns composite metallized polyester films with good barrier properties relative to gases. More precisely, it concerns a biaxially drawn composite metallized film based on polyester and having improved barrier properties to gases, characterized in that the composite comprises a polyester film base of 5 &mgr;m to 50 &mgr;m, directly coated on one of its two faces with a layer including a mixture of a polyvinyl alcohol which has an average degree of polymerization in number equal to or in excess of 350 and a water-dispersible copolyester with sulphonyloxy residues, the layer including the polyvinyl alcohol and the water-dispersible copolyester being in turn coated with a metal layer, the composite film exhibiting a permeability to oxygen, measured at 23° C. under 50% relative humidity, equal to or lesser than 0.4 cm3/m2/24 h. The composite metallized polyester films have, besides their barrier properties, excellent resistance to mechanical stresses, such as in particular crumpling.

Abstract: The invention concerns composite polyester films with good barrier properties relative to gases. More precisely, it concerns a biaxially drawn film, based on polyester and having improved barrier properties relative to gases, characterised in that it comprises a base polyester film of 5 to 50 &mgr;m, coated on one of its two surfaces with a deposit containing polyvinyl alcohol and a water dispersible copolyester with sulphonyloxy units, said composite film having permeability to oxygen measured at 23° C. under 50% relative humidity, not more than 5 cm3/m2/24 h. Said composite films have, besides being transparent and having barrier properties, excellent resistance to mechanical stresses, such as in particular crumpling.