VTT Technical Research Centre of Finland has developed a thin and fully recyclable packaging coating that reduces the need for aluminium.
Developed using the atomic layer deposition (ALD) method, the coating has excellent gas permeation resistance, which makes it suitable for food and pharmaceutical products.
The ALD technology, developed in Finland in the 1970s, has to date been mainly utilised in microelectronics.
ALD facilitates the manufacture of packaging materials that are thinner, lighter and better sealed than traditional barrier materials.
Barrier materials can prevent molecules from penetrating the packaging, which is important when protecting the product from humidity, drying or oxidation.
The barrier ability can be created without an aluminium film, the traditional barrier material that affects recyclability.
For packaging technology, this creates an opportunity to manufacture fully recyclable packages that use fewer raw materials.
The amount of aluminium can be reduced 500-1,000-fold compared with current medicine blister packs.
The use of aluminium affects the pack's recyclability and its manufacture requires a lot of energy.
ALD coatings are thin, conformal and pinhole-free and closely follow the contours of the coated material.
Their thickness can be adjusted to the accuracy of one atomic layer.
The film's 25-nanometre depth makes it bendable and flexible.
Thin bio-based packaging materials produced using this technology have gas-permeability properties similar to those of existing dry-food packages and pharmaceutical blister packs.
The ALD coating allows different functions to be integrated in the packaging material, such as properties that prevent water, oxygen, humidity, fats and aromas from permeating the packaging and protect the surface from stains and bacterial growth.
ALD thus provides savings on raw materials and transport costs.
For example, chocolate wrappers can now be made without the aluminium-coated paper, if the carton wrap is treated with the ALD coating method.
Other thin-film methods can also produce thin coatings; however, their gas permeability is higher and the material is stiffer and breaks easily.
With these competing methods, comparable gas-permeation resistance is possible only if thicker films are used.
The ALD technology can improve the humidity tolerance and performance of bio-polymers, reducing the need for oil-based plastics.
Developed in Finland in the 1970s, the ALD (Atomic Layer Deposition) reactor is a device for the chemical composition of thin films.
It can produce a film with the accuracy of one atomic layer.
The basic materials of aluminium oxide coating are usually trimethyl aluminium and water.
To date, the method has been used as part of the manufacturing process of technical products in the semiconductor industry.
