Bone-in ribs, frozen prawns, a block of aged cheese with sharp corners: these are the products that destroy packaging. Not through chemistry or oxidation, but mechanically — a sharp edge works against the film every time the carton shifts, until one day the pouch gives way and the product arrives compromised. Nylon is the material that prevents that. It is the layer you add when the failure mode you are guarding against is physical rather than chemical, and knowing when to pay for it is one of the more useful skills in specifying flexible packaging.
What nylon brings to a laminate
Nylon — polyamide, abbreviated PA, and often sold as BOPA when biaxially oriented — contributes three things that no other common packaging film delivers together: puncture resistance, a meaningful oxygen barrier, and a wide usable temperature range. It is rarely the cheapest layer in a specification and it is rarely the one that can be removed without consequence.
Key properties
Puncture and abrasion resistance
This is nylon’s defining characteristic and the reason it exists in packaging at all. Oriented nylon absorbs impacts and resists tearing propagation far better than PET or BOPP at equal gauge. In practice, adding a 15µm nylon layer to a structure can be the difference between a 1% and a 6% transit damage rate — and the material cost is almost always lower than the cost of the returns.
Oxygen barrier
Nylon provides a moderate oxygen barrier — considerably better than PE or PET, well short of EVOH or foil. It is good enough to contribute meaningfully to a vacuum pack or a modified-atmosphere pack, but on its own it will not deliver a twelve-month ambient shelf life for a sensitive product.
Temperature range
Nylon works from about -60°C to 150°C, which spans deep freeze through pasteurisation to 121°C retort sterilisation. Very few packaging films operate across that whole band. It is why the same material shows up in frozen seafood bags and in sterilised ready meals — the applications look unrelated but the thermal requirement is served by the same film.
Deep-draw forming
Nylon thermoforms well, drawing deeply without thinning to failure. That makes it the standard top web or bottom web in thermoform-fill-seal packaging for bacon, cheese and processed meat, where the film has to stretch into a cavity before the product goes in.
The moisture problem
Every other discussion about nylon eventually arrives here. Nylon is hygroscopic — it absorbs moisture from the atmosphere — and as it does, three things happen:
- Oxygen barrier degrades. This is the serious one. Wet nylon loses a substantial part of its barrier performance, so a pack designed on dry-condition data can underperform in a humid climate.
- The film dimensionally changes. Absorbed moisture causes slight expansion, which affects registration and can produce curl or wrinkling in the laminate.
- Stiffness drops. Conditioned nylon is more flexible, which sounds harmless but changes how the film behaves on the packing line.
The practical responses are straightforward but need to be planned for: nylon is almost always buried inside the structure behind moisture-resistant layers rather than left exposed, film is stored in controlled humidity, and converters condition and use it within a defined window. If you are qualifying a nylon structure, ask for barrier data at the humidity the product will actually see, not only at 0% RH.
Oriented versus cast nylon
- BOPA (biaxially oriented polyamide) — the standard choice. Orientation raises tensile strength, puncture resistance and barrier. Used in the great majority of laminates.
- Cast / unoriented PA (CPA) — softer and more formable, with better deep-draw behaviour. Chosen for thermoforming applications where the film must stretch significantly.
Common structures and what they are for
PA/PE
The workhorse vacuum and frozen-food laminate. Nylon contributes puncture resistance and barrier; PE seals and provides low-temperature toughness. Typically 15µm or 25µm nylon against 60–120µm PE. We covered this pairing in more depth in Vacuum Pouches: Principles, Materials and Buying Guide.
PA/CPP
The retort structure. Here the sealant is cast polypropylene rather than PE because it withstands 121°C sterilisation. Nylon supplies the toughness and thermal resistance; CPP survives the process and seals.
PA/AL/PE or PA/AL/CPP
Foil added for maximum barrier. Used for long shelf life, retort sterilisation and premium products. The nylon here serves double duty — puncture protection for the pack, and mechanical protection for the foil, which is the foil’s known weakness.
PA/EVOH/PE
A transparent high-barrier structure. Nylon handles toughness, EVOH handles oxygen, and the whole thing stays clear. It is the usual answer when a product needs barrier but the brand wants the customer to see it.
Choosing a gauge
Nylon is typically specified at 15µm or 25µm. The 15µm grade covers most frozen food, cheese and vacuum applications and is the default on cost grounds. Moving to 25µm is justified for heavy bone-in products, sharp frozen items, large-format packs where the film spans a wide unsupported area, and any application with a history of transit punctures. If you are currently experiencing puncture failures, the cheapest first move is usually a gauge increase rather than a structural redesign.
When nylon is worth the cost
Nylon costs more per kilo than PET or PE, so it should earn its place. It is clearly justified when: contents have sharp edges or protrusions; the pack is vacuumised, which puts the film under constant stress against the product; the distribution chain is long or rough, as with e-commerce; the product is frozen and handled cold, where films are at their most brittle; or the process involves retort temperatures. It is probably not justified for dry, smooth, low-abuse products on short distribution — a well-specified PET/PE will do the job for less.
Dealing with punctures or leakers in transit? Contact Us — send us the product and the failure rate and we will advise on gauge and structure.