Optical properties, birefringence and the effect of pleochroism in multilayer coatings and plastic packaging made of polyvinyl chloride of domestic production are described. Film pleochroism is most intensely manifested in the flux of light passing through several layers of film and has a wide range of colors when several layers of polyvinyl chloride shrink film are combined in materials for flexible transparent packaging and biaxially oriented isotactic polypropylene film. It has been established that the color of several layers of polyvinyl chloride shrink film in transmitted polarized light changes under the influence of organic solvents. This phenomenon is proposed to be used for hidden marking of packaging or labels and combating counterfeit production of consumer goods sold to the public in a retail network of stores. achieving the visibility of security marking and the ability to identify goods by trademark or using a bar code. The color difference between multilayer films of polyvinyl chloride before and after treatment with a volatile solvent reaches 35 units with two or more layers, determines the bright color of the trademark and/or sufficient contrast of the code used for hidden marking of packaging or labels detected in polarized light. The application of the Florey-Huggins criterion for quantitative assessment of color change in a package of polyvinyl chloride films under the influence of organic solvents is shown. The values of the modulus of elasticity, kinetics and the degree of maximum swelling of the polyvinyl chloride film in 10 organic liquids of various chemical structure are measured Flory-Huggins.

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