Multilayered packaging

Multilayer packaging was developed in the mid-20th century to overcome the performance limits of single-layer materials. An early example is the aseptic carton introduced by Tetra Pak in the 1960s, combining paperboard, polyethylene, and aluminium foil. == Types ==

Multilayer packaging varies by material combination and application. • Multi-wall paper sacks – layers of kraft paper, sometimes with polyethylene, for cement, fertilizer, and bulk foods • Laminated cartons – paperboard with aluminium foil and plastics, used for milk, juice, and syrups • Plastic bottles and tubes – combinations such as PET/EVOH/PE, used for sauces, juices, and cosmetics • High-barrier pouches – flexible laminates with PA, EVOH, or oxide coatings, used for sterilized or ready-to-eat meals == Food packaging ==

Multilayer systems are widely used for food preservation because they block oxygen, light, and moisture. EVOH is often used as an oxygen barrier, while polyolefins provide moisture resistance. Another application is modified atmosphere packaging (MAP), which replaces air with controlled gases such as nitrogen or carbon dioxide to slow microbial growth. == Manufacturing ==

Three main processes are used: • Coextrusion – simultaneous extrusion of polymers, often with tie layers • Lamination – bonding prefabricated films, foils, or paper layers with adhesives or heat • Coating – applying functional layers onto substrates, == End-of-life ==

Multilayer packaging is difficult to recycle because of its mixed-material structure. As of 2018 less than 5% was recycled at scale, with most waste incinerated or landfilled. Possible approach include solvent-based separation, compatibilizers, and enzymatic depolymerization of PET. == See also ==