Core Structure of Multilayer Films

Typically 3-7 layers with specific functions:

Layer Position	Primary Function	Common Materials
Outer Layer	Protection, printability, durability	PET, PP, PA (Nylon), Paper
Barrier Layer	Block oxygen, moisture, aromas	EVOH, PVDC, Aluminium foil, Metallized film, PA
Tie/Adhesive Layer	Bond incompatible layers	Specialized tie resins (like maleic anhydride grafted PE/PP)
Seal Layer	Heat sealing, food contact	LDPE, LLDPE, mLLDPE, ionomers (Surlyn®), EVA

Common Multilayer Structures & Applications

Structure	Typical Composition	Key Properties	Common Applications
PET//PE	PET / Adhesive / PE	Good moisture barrier, printable, stiff	Dried foods, nuts, cookies
OPP//PE	Biaxially Oriented PP / PE	Good moisture barrier, clear, cost-effective	Crackers, snack bars
PET/EVOH/PE	PET / Tie / EVOH / Tie / PE	High oxygen barrier, moisture protection	Tomato sauce, juices, deli meats
PA/PE	Nylon / PE	Puncture resistant, good oxygen barrier	Vacuum-packed meats, cheese, fish
PET/Met/PE	PET / Metallized layer / PE	Excellent light & oxygen barrier, flexible	Potato chips, coffee, chocolate
Paper/PE/Alu/PE	Paper / PE / Aluminum foil / PE	Total barrier, stiff, opaque	Aseptic liquid packaging (juice boxes)
PP/EVOH/PP	PP / Tie / EVOH / Tie / PP	Retortable, high barrier, microwave-safe	Ready meals, pet food, soups

Performance Advantages vs. Monolayer Films

Property	Multilayer Improvement
Shelf Life	2-10x extension through tailored barriers
Strength	Combine puncture resistance with sealability
Cost	Optimize material use (expensive barrier only where needed)
Functionality	Incorporate peelable seals, easy-open features
Print Quality	Superior graphics on outer layers