Metallisation

Metallisation refers to aluminium-metallised barriers that are applied to a carrier film (e.g. BOPP or PET) in nanometre-thin layers using vacuum coating (PVD). This process enables very high oxygen, water vapour and light barriers to be achieved using a nanometre-thin aluminium layer.

Properties

Application

Metallised barrier films are often used as a functional middle layer in composite or mono-materials (PETmet/PE, OPPmet/CPP) where, in addition to an oxygen and water vapour barrier, a light barrier is also required (e.g. for coffee, snacks and powdered products).

Barrier performance

Metallised films enable ultra-high barriers with ORT and WVTR values of <= 0.1. The barrier performance depends on the metallisation quality, layer thickness, overall composite and test conditions. During film processing, mechanical stress can reduce the barrier performance – this is caused by creases and material stretching.

Recycling

Metallised PP-based structures such as OPPmet/CPP may be suitable for recycling where the complete packaging structure is compatible with the intended PP recycling stream and meets the applicable design-for-recycling criteria. Metallisation can affect NIR sorting, particularly when the metallised surface is externally visible. Where the metallisation is covered by printing or positioned within the material structure, sortability should be assessed for the specific packaging design and the intended recycling stream. For private end consumers in Germany, empty plastic flexible packaging with metallisation should generally be disposed of via the Yellow Bin or Yellow Bag; in some regions, a recycling bin (Wertstofftonne) is provided instead.

Depending on the recycling process and the specific packaging structure, metallised flexible packaging may produce recyclate with reduced optical quality, such as greying or clouding. Further processing may still be possible, but the resulting recyclate may be more suitable for applications with lower optical requirements.

Sources as of 23 January 2025: