Technology of forming and modifying multilayer metallized packaging materials
Packagings from composite plastics, including metallized plastics, find ever wider use in meat and food industries. Often they are given the preference over traditional articles from metal and plastics owing to their low specific mass, high mechanical strength and corrosion resistance. Metallized polymer materials are dielectrics. They possess an increased resistance to the action of moisture, organic solvents, high temperatures, gas and vapour permeability during the boiling of packagings, as well as endow materials and articles with specific performance properties – resistance to the action of bacteria and molds, protection of food products from ionizing radiation. To obtain a metal layer, use is made of such metals as aluminium, copper, nickel, platinum, tin, lead, zinc, as well as metal alloys. A topical problem is protection of the surface of these materials, the purpose of which is to decrease the number of formation defects, to increase the resistance to cracking, scratching, as well as atmospheric and biochemical resistance of materials, to improve the decorative properties. One of the promising and non-traditional ways of solving this problem is to develop polymer composite materials with high adhesion to the metallized layer, resistant to the action of sterilization. This makes it possible to simplify the technological process of fabricating multilayer packaging materials as the result of reducing the number of layers and, respectively, stages of extrusion lamination and adhesive bonding of film materials with foil or the metallized layer, as well as to rule out the labour-intensive and expensive treatment of the surface of substrate with a metallized layer and to reduce the treatment temperature. The use of a lacquer layer for protection of combined packaging materials makes it possible to develop systems, which can successfully compete with foiled packagings by their properties, technical and economic parameters and fields of applications. Calculations based on the data by Russian enterprises show that transition from the production of combined materials based on foil to metallized packagings ensures a significant economy of raw materials.