The creation of nanophotonic systems for printed smart food packaging
Nanophotonic systems and printing technologies are developed to manufacture smart food packaging, which enhance shelf life of foods without the need for additional processing, and indicate the current state of a packaged product, i.e. its suitability for consuption, by changing the optical properties of a printed image (color, luminescence intensity).
Recipes are developed of model nanophotonic compositions intended for the manufacture of smart printed packaging, and the technological requirements are determined for their composition for printing labels with nanophotonic elements on functional packages basised on ZnO nanocrystals with a concentration of 0.02 mol/Ll and polyvinyl pyrrolidone with a molecular weight M = 360000 g/mol.
Photophysical properties of the nanocomposites are investigated in the presence of substances that emerge in the process of storage of food products. It is determined that nano-ZnO reduces the luminescence intensity in contact with substances that emerge in spoilage process of protein foods (amines, ethanol) and the pH change. Due to its antimicrobial and UV barrier properties, nano-ZnO can perform several functions in packaging. Other organic dyes are also investigated, in particular rhodamine, which can also serve as indicators of food freshness.
Methods are developed of printing and the fixing of printed images with nanophotonic elements using modern printing techniques, and taking into account the design aspects of marking smart packaging with nanophotonic elements.
It is determined the influence of the properties a printed material (the surface microstructure, porosity, whiteness of paper, the thickness of the polymer film, the surface roughness of aluminum foil) on the optical characteristics of the printed layers. It is determined how changing technological parameters of the printing process (thickness of coating, concentration of the luminescent component in the composition, printing speed) can compensate for non-optimal values of a substrate with the aim of obtaining predetermined optical characteristics of printed layers with nanophotoniс elements.
The processes of printing nanophotonic elements is investigated. The regularities are determined of the influence of technological parameters of the printing process of production of markings with nanophotoniс elements on their optical properties (which are characterized by changes in the luminescence intensity and color under the influence of technological parameters), which allows to predict optical characteristics of the resulting printed functional packages depending on the parameters of the printing process.
The mathematical model is developed of the influence of technological parameters of drying (temperature and time of drying) of the printed impressoins with nanophotonic elements on their optical characteristics (luminescence intensity and color) based on the regression equation, which provided the possibility to predict optical characteristics of the obtained markings of functional packaging, depending on the drying parameters. There is determined the recommended temperature (60°C) and drying time (4-15 sec) to obtain the most possible luminescence intensity of the printed images with different ink layer thickness on the printed impression (2-100 µm).
The mathematical model is developed to ensure the optical characteristics of printed impressions with nanophotonic elements, taking into account the parameters of the technological process of marking printed functional packages (prepress and printing processes) with optical characteristics of the resulting printed elements of functional packages. This allows producing printed functional smart packaging with predetermined optical characteristics.
The method is developed for calculation of technological parameters of printing of nanophotonic elements for smart packaging with predetermined photoluminescent characteristics, which is described by the created algorithms.
With the purpose of automation of technological calculations the software is developed for calculation of technological parameters of printing images with variable optical characteristics, a certificate of copyright for which is obtained; it allows prediction of the optical characteristics of printed markings with nanophotonic elements by the known technological parameters, and determination of the process parameters of obtaining markings for smart packaging with the predetermined optical characteristics.