In recent years, the intensity of debate surrounding the eco-friendliness especially of building materials has increased. All the results from trials of prepainted aluminium under various weather conditions e.g. in building application have confirmed that it poses no risk to the environment.

The aluminium base material is protected by a coating. If areas become exposed, e.g. due to installation errors, the aluminium protects itself through a reaction with the oxygen or water vapour in the air to form a thin but dense oxide layer (Al2O3). This oxide layer protects the base material from metal erosion., therefore there will be no contamination of groundwater like heavy metals. Condensation presents no risk.

Aluminium is non-toxic and poses no nutrional risk. According to prevailing German food laws, the use of aluminium is not subject to any restrictions. Aluminium has no detrimental effects on plants, animals, groundwater or surface water.

The pigments used are normally non-hazardous; in some cases they are even safe for use with foodstuffs.

For processing reasons, Novelis prepainted aluminium is in generally covered with a removable, UV-resistant polyethylene protective film. This protective film is eco-friendly, groundwater-neutral and can be recycled.

Exkurs: PVDF-paint systems

PVDF paints are used especially for outside building applications. The PVDF coating features good shaping properties and outstanding resistance to weather conditions.

The PVdF coating comes in a 80/20 quality (80% PVdF + 20% acrylate) which is used for Novelis building applications, and a PVdF coating in 70/30 quality (70% PVdF + 30% acrylate). Generally speaking, the higher the PVdF content, the better the resistance to weathering and annual erosion.

PVdF is the only conventional, thermoplastic Fluor-Polymer-Resin, which is commercially widely used for weather resistant lacquers. For the production of the lacquer the resin is turned into a solution by using a solvent with high polarity, which than is blended with a special acrylic resin with a proportionate weight of 20 – 30%.

There are different ways to describe the compatibility of the PVdF-lacquers with the environment.

The shape of the product is observed in 5, 10 and 20 years terms. This can be done by going from today backwards, as enough projects and samples are available. This is a very complicated and time consuming procedure for the evaluation of the decomposition of the lacquer, since under certain circumstances the results can be contradicting, as they depend on the location and the kind of pollution. Furthermore it must be stated, that PVdF has an extremely low wear of the resin, which is calculated with only a few microns (µm) per 10 years.

Another possibility is to analyse the lacquer itself and to examine its ingredients in respect to their compatibility with the environment.

PVdF-lacquers mainly consist of:

• a Fluor-polymer
• an acrylic type
• pigments
• catalysers
• additives

The Fluor-polymer is, after being washed down from a roof by weathering, not soluble in water. As a consequence no contamination of the ground water takes place. The PVdF-particles remain in the ground and are environmentally neutral.

The acrylic can be dissolved from the PVdF-surface by UV-penetration and destroyed by UV-radiation. It is not known that these particles are intolerable by the environment.

In general the pigments in the lacquer are absolutely harmless, they are even suitable for food. Harmful pigments are being avoided and not used at all. The use of lead-chromate for yellow colours, for example, is state of todays technology.

Catalysers are not used for Novelis building products paints, and therefore of no danger.

The additives undergo a detailed procedure of investigation at the moment. But it is almost certain that danger to the environment will not be detected.