Abstract: Polyolefinic films having improved impermeability characteristics to gases and vapors, said films being coated on either one or both its surfaces by a layer of a copolymer containing functional hydroxylic groups, functional acid carboxylic groups and optionally--esteric groups and obtained by hydrolysis of copolymers consisting of an unsaturated ester and of an unsaturated acid or corresponding anhydride.

Abstract: Films comprising alpha-olefin polymers, such as polypropylene consisting essentially of recurring propylene units and having a substantial crystalline polypropylene content, and in particular isotactic polypropylene, are rendered poorly adhesive to the welding bars of automatic and semi-automatic machines conventionally used for the manufacture of containers, envelopes, bags, vessels and, in general, other manufactured articles useful in the packaging industry, by coating the films by a mixture of a copolymer of a vinyl ester with an unsaturated acid, a terpolymer of an alkyl acrylate, an alkyl-methacrylate and an unsaturated acid and a cross-linking amine.