Adviser about Flexible packaging

Aluminium (ALU) is used in packaging film as a thin functional layer when particularly high levels of protection are required. Aluminium barriers provide the ultimate protection against oxygen, water vapour and light. The most common application is as a middle layer in PET/ALU/PE composite materials; which protects the sensitive aluminium and at the same time enables the best processing properties.

Properties

Application

Aluminium foil is usually used between different plastic layers (e.g. PET/ALU/PE) to provide ultra-high barriers for particularly sensitive products. The PET serves as a printing foil, the PE as a wear layer with good sealing properties. Aluminium barriers are mainly used in the pharmaceutical sector, for sensitive foods such as baby food, or as corrosion protection in the industrial and electronics sectors. This is particularly the case when, in addition to oxygen and water vapour barriers, very high light and aroma barriers are also required.

Barrier performance

Aluminium barriers achieve absolute barriers against oxygen and moisture from a layer thickness of 17 µm. In common application thicknesses of, for example, 9 µm, OTR values of 0.05 and WVTR values of 0.03 can be achieved. Aluminium barriers are not affected by moisture or temperature, but are sensitive to mechanical stress. Individual creases and pinholes can massively reduce the barrier performance.

Recycling

From the point of view of mechanical PE/PP recycling, aluminium foil is a non-compatible foreign material (no longer a ‘pure’ polyolefin mono-material). In its current film guidelines, RecyClass classifies aluminium as ‘incompatible’ with PE and PP films – not recyclable.

Such composite materials are disposed of in the yellow bag so that valuable raw materials are not wasted – the aluminium is recovered via pyrolysis, but the plastic content is not yet recycled.

Sources as of 23 January 2025: