PET (polyethylene-terephthalate) is a hard and clear polymer material with extremely good mechanical features. It shows excellent tear resistance; it can resist to high pressure volumes without braking, which is used in the production of packages for beverages – PET bottles.
PET material is suitable also for the production of extruded foils. Subsequent biaxial stretching of the foil (in both directions) improves significantly the strength in both directions. It forms the required packaging material known for example from gift packs, or as a baking foil. In the foil form, PET is very resistant against water steam and gas permeability providing protection to packaged products, it also resists to effects of oils and fats included in packaged food-stuff.
PET may be combined with other materials and create multi-layer packages, the features of which are modified for the specific application – packaging of aromatic spices, cheese, smoked-meat products, etc. On customer’s request, foils may have different colours, may be imprinted, metal-coated (cosmetic industry, toothpastes), or laminated (packages for pet feedstuff).
Typical examples of PET applications include:
Fibres in textile industry – dressmaking, winter jacket wadding (padding).
Beverage bottles, in particular for sparkling and alcohol-free beverages.
High-speed boiling pouches, precooked food bags, packages for non-perishable food.
PET counts among well recyclable materials. PE bottles sorted from the municipal waste are most frequently reprocessed into fibres.
Aluminium (chemical symbol Al, Latin title Aluminium) is a very light metal of whitish-grey colour, very good conductor of electric current, used widely in electronics and also in alloys for the aircraft industry and many other applications.
Aluminium is used mainly due to its relatively high chemical resistance and low weight. After rolling-down into a thin foil it is known as a kitchen foil called “alobal”, which is used in baking and roasting or as a protective packaging material for various applications.
Aluminium is also used for the production of flexible packaging foils. Aluminium layer is usually steamed onto a plastic foil by electrical discharge in vacuum.
PE (polyethylene) is the most frequently used plastic in the world. Its annual production exceeds 90 million tons. It was developed in 1933. This invention was essential for the development of modern plastic materials, which we cannot imagine our life without anymore. From the chemical point of view, the polyethylene structure is very simple, therefore it can be produced relatively in an easy and inexpensive way. According to its density, polyethylene is classified into two major types, so-called low-density (LDPE) and high-density (HDPE), the third type is the so-called linear low-density PE (LLDPE).
Both PE types can be processed easily using plastic-processing technologies, and manufacture products of various shapes and sizes from them. In general, polyethylene has an excellent strength, high toughness, and ductility; products may be transparent or coloured with pigments. The common PE processing method is extrusion (2D products) and injection moulding (3D products).
The best-known polyethylene applications include:
Flexible packages – bags for fresh and frozen food products, shopping bags, extensible foils.
Solid packages – bottles for detergents and cosmetics, cans, barrels, large-size containers.
Daily need products – minor kitchen dishes.
Tubes and pipes
Polyethylene may be recycled. It is widely present in the communal waste, therefore there are efforts to sort it (yellow container for sorted waste) and reuse.
PP (polypropylene) is the second most frequently used material in Europe. Its share in consumption of plastic materials ranges about 20 %. Polypropylene is By its features and use, polypropylene is similar to polyethylene, therefore both of these polymers are classified in the same group indicated as polyolefins. Unlike PE, PP however features higher strength and consistency, and since its melting temperature is higher, it shows good temperature stability. PP consistency imparts good dimensional stability to products.
Polypropylene can be found almost anywhere: in packaging materials, household appliances, clothing, means of transport, and many other products. More than half of the world PP production is used for packages. It is also used in technical applications.
It is used among others in the production of:
Packages – flexible foils, pots for dairy products and beverage machines, moulded trays, package caps, bottle caps, bags, notebook covers.
