BOPA — biaxially oriented polyamide — is the film you specify when the pack has to survive. It has the highest puncture and tear resistance of any common flexible substrate, a gas barrier that rivals EVOH in thin structures, and a service range of −20 °C to 120 °C. Nothing else in the standard flexible-packaging toolkit combines toughness, gas barrier and thermal range in one web.
The trade-off is honest and easy to design around: BOPA is a poor moisture barrier on its own. That is exactly why it is almost always used as the middle or outer web of a laminate, paired with a PE or metallized layer that handles the water vapour. Used that way, BOPA is the structural backbone of vacuum packs, retort pouches, medical packaging and any pack that travels badly.
OLUNRO supplies BOPA film for packaging in converter and end-user volumes, with in-house metallizing and lamination available on the same site.
How BOPA film is made
BOPA is made from PA6, produced by the ring-opening polymerisation of caprolactam (CPL). From there:
- Melting — PA6 chips are melted
- Extruding — the melt is extruded into a thick cast sheet
- Stretching — the sheet is drawn biaxially, using sequential or simultaneous stretching technology
- Result — biaxially oriented PA (BOPA) film
The stretching step is what converts ordinary nylon into BOPA. Drawing the sheet in both machine and transverse directions aligns the polymer chains, and aligned chains are what deliver the tensile strength, the puncture resistance and the gas barrier that nylon is specified for. Sequential and simultaneous stretching produce measurably different film properties — if your application is at the edge of the spec, tell us which you need.
Why PA nylon film is widely used
| Property | What it means commercially |
|---|---|
| Excellent tensile strength and puncture resistance | Fewer leakers and returns on abraded or vacuum-loaded packs |
| Superior gas and aroma barrier (O₂, N₂, CO₂) | Longer shelf-life on oxygen-sensitive contents without adding a ply |
| Wide application temperature range −20 °C to 120 °C | One structure covers freezer, ambient and retort-adjacent duty |
| Excellent performance on printing and lamination | Clean ink adhesion and reliable lamination without special handling |
| Favourable flexibility, anti-grind | Withstands handling and flexing rather than pinholing |
| High transparency and glossiness | Clear packs and high-quality print without a dulled appearance |
| Endures acid, alkali, grease and common organic solvents | Suitable for aggressive and greasy contents, and for chemical contact |
Where BOPA is specified
| Application | Why BOPA |
|---|---|
| Vacuum packs (meat, cheese, fish) | Puncture resistance through bone and edge contact; gas barrier for colour retention |
| Retort and pasteurised pouches | Survives the thermal cycle without losing structure |
| Medical and diagnostic packaging | Toughness, sterilisability, clear appearance |
| Liquid and paste sachets | Flex-crack resistance on form-fill-seal with sharp corners |
| Aseptic and bag-in-box liners | Strength under hydraulic load |
| Metallized laminates | As a metallized substrate it delivers the best moisture-barrier gain in our range (see the WVTR table on our metallized films page) |
Working with BOPA: three practical notes
Pair it for moisture. BOPA’s WVTR is high — a 15 µm film transmits 250–290 g/(m²·24h) at 40 °C. Metallizing drops that to 0.5–0.8. If your contents are moisture-sensitive, do not run bare BOPA as the sealing web.
Ask for the stretch method. Sequential and simultaneous biaxial stretching give different balances of tensile, shrinkage and barrier performance. It is a legitimate specification field, not a detail.
Confirm flex-crack performance. BOPA is tough, but the metallized or coated layer on it is not infinitely so. If the pack will be handled hard or the pouch has sharp corners, ask us to confirm pinhole resistance on the exact structure.
Why buyers shortlist OLUNRO
- Metallized and coated BOPA from the same source. The barrier upgrade and the base film come from one supplier, so the laminate is qualified once.
- Converter and end-user volumes. Big or small orders are both acceptable — trial rolls are not a special favour.
- Processability confirmed before volume. Tell us the machine and the seal conditions and we confirm the roll runs.
- Full-chain traceability. Because our PCR PE line runs to GRS under Intertek TE-00352946, documentation discipline is already part of how we operate.
Request a BOPA sample
Tell us the structure, the contents and the machine. We will confirm the grade, supply a specification sheet, and send a sample roll for your own trials.
Contact: info@olunropack.com · +86 532 6776 6956