Abstract: Polyolefin polymeric packaging film is provided with a structure varying across its thickness from monolithic to porous with a density gradient ranging from .rho. to (1/2 to 1/4).rho., where .rho. is the density of monolithic polyolefin. The packaging film is characterized by a varying structure across its thickness. Such a film possesses the functions of a multi-layer film, but has none of the disadvantages of the latter associated with different adhesion of the layers, possible delamination in the course of storage and use, as well as the complex manufacturing process of a multi-layer film. The gradual transition of the porous structure of polyolefin to the poreless one from one surface of the film to another ensures distribution of liquid-phase specific additives along the film thickness.

Abstract: A process of producing a tubular polymeric anticorrosion film which includes extrusion of a mixture of a thermoplastic polymer with a corrosion inhibitor in a liquid phase or with a solution thereof in a plastifying agent employed in an amount exceeding the limit of compatibility with the polymer, blowing this melt into a tubular film upon cooling, application of a layer of an enamel or a varnish incompatible with the thermoplastic polymer onto the external surface of the formed tubular film before the line of crystallization, which layer has a difference of the solubility parameters in respect of said corrosion inhibitor or a solution thereof in a plastifying agent of not more than 8.