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Multi-layer structure
Also known as: multilayer film, laminate structure, packaging structure, 2-ply, 3-ply, duplex, triplex
A multi-layer structure is the stack of different films in a flexible pack, each doing a job such as print, barrier or sealing, e.g. PET/ALU/PE.
A multi-layer structure describes the sequence of materials in a flexible package from outside to inside, written like PET 12 / ALU 9 / PE 80 (material and thickness in microns).
Typical roles
- Outer layer: PET, BOPP or kraft paper that carries the print and gives stiffness and finish.
- Middle layer: aluminium foil, metallised film, EVOH or OPA for barrier and puncture resistance.
- Inner layer: PE or CPP that touches the product and forms the heat seal.
Layers are joined by lamination or produced together by co-extrusion.
How many layers?
Two-ply structures such as BOPP/CPP suit dry snacks and short shelf life products. Three-ply structures like PET/ALU/PE are common for coffee, powders and supplements that need strong protection from oxygen, moisture and light. More layers mean more protection but also higher cost.
Mixed-material laminates are hard to recycle mechanically. If recyclability matters to your brand, ask about mono-material options and compare performance and price with your converter at the quotation stage.
Frequently asked
What does PET/ALU/PE mean?
It is a three-layer laminate: PET on the outside for print, aluminium foil in the middle for barrier, and PE on the inside for sealing.
Are multi-layer pouches recyclable?
Laminates made of different polymers are generally difficult to recycle. Mono-material PE or PP structures are designed to be more recyclable.
Related terms
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