The ALD technology was developed in Finland in the 1970s and has been utilised mainly in microelectronics to date but work at VTT has demonstrated that the coating is applicable to trays, folded boxes and tubes designed for food and medical products.
Lead researcher Professor Ali Harlin told this publication that commercialisation projects are initially focusing on pharmaceutical packaging applications but that trials have shown that the coating can also be used in polymers for the packaging of flavour and aroma sensitive foods such as chocolate and coffee.
He maintains that the ALD coating provides savings on raw material and transport costs as the amount of packaging material can be reduced and recycling of the packaging is made easier.
Chocolate wrappers, for example, can now be made without the aluminium-coated paper, if the carton wrap is treated with the ALD coating method, explained Harlin.
Developed using the atomic layer deposition (ALD) method, the coating has excellent gas permeation resistance, “The ALD forms a very even ceramic layer, which acts like a glass and thus has high oxygen, moisture and grease barrier properties,” he said.
The barrier layer formed by ALD, continued Harlin, is not designed to be in direct contact with the food product but is instead placed in between the polymer layers so migration into the food product is not a factor.
He explained that the ALD coating is nanotechnology based and has a thickness of 25nm rendering the protective layer bendable and flexible. It is produced, he added, by means of controlled stacking atoms on each other in the film forming deposition process.
“As the ALD we are using functions at low temperatures it is suitable for various kinds of polymers, both natural and synthetic forms,” he continued.
However, he said that the ALD technology can improve the humidity tolerance and performance of bio-polymers, thus reducing the need for oil-based plastics.