The ALD thin coating considerably reduces the need for aluminium in packaging solutions
VTT Technical Research Centre of Finland has developed an
environmentally-friendly packaging coating solution. Especially suitable for
food and pharmaceutical packaging, the coating offers a new method for
manufacturing fully recyclable, thin, light and air-tight packaging materials.
Developed using the atomic layer deposition (ALD) method, the coating has
excellent gas permeation resistance and as such it is particularly suitable
for food and pharmaceutical products. The ALD technology, which was developed
in Finland in the 1970s, has been utilised mainly in microelectronics to date.
ALD facilitates the manufacture of packaging materials which are thinner,
lighter and better sealed than traditional barrier materials. Barrier
materials have the ability to 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 which 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
to 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 they closely follow the
contours of the coated material. Their thickness can be adjusted to the
accuracy of one atomic layer. Thanks to the thinness of the film (approx. 25
nanometres), the protective layer is 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
By using ALD coating, different functions can be integrated in the packaging
material, such as properties which prevent water, oxygen, humidity, fats and
aromas from permeating the packaging and protect the surface from stains and
ALD thus provides savings on raw material and transport costs, as the amount
of packaging material can be reduced. 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 a part of the manufacturing process of technical products in
VTT's Video clip on ALD