A conventional high-barrier flexible pack is built from three plies: an outer print web, a barrier web, and an inner sealing web. Each ply has to be bought, laminated, handled and inventoried. PE metallized film — vacuum metallized polyethylene, usually shortened to VMPE — collapses that structure to two, by moving the barrier function into the layer that was already doing the sealing.
The result is one fewer ply, less total material, and a structure that runs on the same converting and filling machinery. The barrier does not disappear; it relocates.
What VMPE film is
VMPE film is a polyethylene film metallized by the vacuum metallizing process: aluminium is evaporated under vacuum and condenses onto one face of the web, while the reverse face keeps a high-strength sealant surface. A single web delivers both the barrier and the seal.
| Element | Detail |
|---|---|
| Base polymer | LLDPE (linear low-density polyethylene) |
| Side A | Vacuum-deposited aluminium — moisture, oxygen and light barrier |
| Side B | Sealant surface — high seal strength |
| Structure role | Barrier and sealing web in a two-ply laminate |
Why LLDPE as the base? LLDPE gives a good balance of toughness, flexibility and heat-seal performance, and it tolerates flexing without the brittleness that can crack a deposited metal layer. A metallized layer has no structural strength of its own — it survives only as long as the film underneath it flexes rather than fractures.
Supply specification
| Parameter | Value |
|---|---|
| Thickness | 40, 60, 70, 80 µm standard. 40 µm is the thinnest we metallize. |
| Custom thickness | on request, 10 t minimum |
| Optical density | 2.3 |
| Seal strength | 8.7 N/15 mm |
| WVTR | 2.1 g/(m²·24h) |
| Web width | 3,000 – 3,200 mm |
| Minimum order, standard gauges | 1,000 kg |
| Sampling | 15 – 20 days |
| Recycled content | GRS-certified PCR grades, Intertek TE-00352946 |
Test conditions, because the numbers are meaningless without them. Seal strength is measured with the upper sealing knife at 120 °C and the lower knife at 80 °C, 1.0 s dwell and 0.2 MPa. WVTR is measured on 40 µm film at 20–28 °C and 40–60 % relative humidity. A WVTR quoted at 38 °C / 90 % RH would be a different measurement of the same film, and it would not be comparable to this one.
Why there are two MOQs. Standard gauges ship from 1,000 kg. A gauge outside those four means changing the production run, and 10 tonnes is the quantity at which that change becomes economic — it is a constraint of the line, not a sales threshold.
On the barrier figure. The WVTR above is for the film as supplied, at 40 µm. Once it is laminated, printed and sealed, what the pack transmits depends on the whole structure rather than this one number — see why the datasheet figure is not the figure in the pack.
What this table does not cover. Adhesive systems, ink compatibility and finished-pouch performance are quoted per project, because they depend on your outer web and your machine. Send the structure and the contents, and we will quote against both.
Why three layers became standard
The three-layer build exists for a reason, and it is worth being precise about it. No single film does everything:
| Function | What is needed | Typical ply |
|---|---|---|
| Print surface and mechanical protection | Smooth, printable, abrasion-resistant | BOPP or PET |
| Barrier | Moisture, oxygen, light block | Metallized PET, foil, EVOH |
| Sealing | Low seal-initiation temperature, hot-tack, contamination tolerance | PE, CPP |
Three functions, three materials — and in a metallized PET barrier web, three layers of different chemistry. That structure performs, and it is why it became the default. It is also why it is expensive to make, hard to inventory and, under current recycling rules, effectively impossible to recycle.
How two layers carry the same duties
Laminated to a BOPP or PET outer web, VMPE divides the work like this:
- BOPP or PET outer web — print surface, mechanical protection, and stiffness
- Metallized polyethylene inner web — the barrier and the seal, in one ply
The barrier is deposited directly onto the polyethylene that will face the product, so there is no separate barrier ply to buy, laminate or inventory. One web, two jobs.
Low-temperature performance
VMPE film’s cold resistance is very good. It can be used normally across the range −40 °C to +80 °C, and — critically — it does not become brittle and hard in cold conditions, so the bag does not burst in winter.
This is a real operational failure mode, not a specification curiosity. In cold-chain distribution and in cold climates, ordinary PE grades stiffen to the point where a filled bag cracks at the fold or the seal during handling. A film qualified to −40 °C removes that failure from your winter returns list.
Specify it when: the pack travels through frozen or unheated distribution, is stored in an unheated warehouse, or ships in winter to a cold-climate market.
Lamination options
VMPE film can be laminated directly with:
| Outer web | Typical reason |
|---|---|
| PET | Print quality, stiffness, high-temperature tolerance at the seal bar |
| OPP | Economical print web for snack and confectionery formats |
| Nylon (BOPA) | Puncture and flex-crack resistance for demanding packs |
Each pairing shifts the balance of stiffness, print quality, cost and mechanical protection. In all three cases the vacuum metallized polyethylene web supplies the barrier and the seal.
Note on side orientation. The metallized side is a barrier surface, not a sealing surface. Lamination orientation determines whether the metal faces the product or the outer web, which in turn affects how much barrier the pack actually delivers. Confirm the intended orientation with us before finalising the structure.
- Excellent barrier properties and sealant performance
- Suitable for VFFS and HFFS applications
- Applications include stand-up and peg-display pouches
Where the savings come from
Material. One fewer ply means less film per pack. The saving is not just the cost of the third film — it is also the adhesive, the solvent and the energy consumed laminating it.
Production steps. Each additional ply is a lamination pass. Removing one removes a full pass from the process, with the associated labour, machine time and yield loss.
Lead time and complexity. A two-ply structure has fewer components to source, stock and trace. Changeovers and inventory management get simpler, and simpler supply chains move faster.
Emissions. Fewer lamination passes and less solvent use means lower VOC emissions — the environmental argument and the cost argument point the same direction here.
What you give up — and when that matters
A two-layer structure is not a free upgrade. Be clear about the boundary:
- Barrier ceiling lowers slightly. A vacuum metallized PE layer delivers a real moisture and light barrier, but a metallized PET barrier web in a three-ply laminate still wins on absolute performance. If the shelf-life target is aggressive, keep three plies.
- Stiffness changes. The structure handles differently on the machine. Feed, tension and forming settings will need confirming.
- Sealing conditions must be re-qualified. The inner web is different, so seal-initiation temperature, dwell and pressure need a trial.
The practical rule: two-layer PE metallized structures are the right answer for short-to-medium shelf life with a demanding cost target. They are the wrong answer when the contents are highly oxygen-sensitive or the shelf life is measured in years.
Sealing and conversion: what to qualify
Changing the inner web changes the seal. Before committing to volume, confirm:
- Seal-initiation temperature and hot-tack — measured on your machine, at your line speed, not on a data sheet.
- Seal through contamination — powders, oils and greasy contents are the usual cause of weak seals on polyethylene inner webs.
- Web tension and forming — the two-ply structure handles differently through the forming collar on VFFS; feed and tension settings typically need adjustment.
- Pinhole and flex-crack resistance — if the pouch has sharp corners or will be handled hard, verify on the finished structure rather than the flat film.
We confirm processability before volume. Send us the machine and the sealing conditions and we will run the trial rather than asking you to discover the settings yourself.
Where the structure fits
The two-ply build is compatible with a wide range of packaging, and with both BOPP and PET outer webs:
- Snacks and savoury products
- Confectionery
- Household goods
- Dry foods and powders
- Stand-up and peg-display pouches
- Vertical and horizontal form-fill-seal (VFFS / HFFS)
One more reason: recyclability
Removing the third ply does more than cut cost. The traditional three-layer structure has been simplified into an innovative two-layer build — and it also saves energy and protects the environment by reducing the emission of VOCs, because one lamination pass is removed from the process.
Many brands and retailers have committed to fully recyclable packaging on a fixed timeline. Laminating a vacuum metallized PE web with a plain polyethylene sealing web is one of the few routes to a recyclable structure that does not give up barrier.
Because the VMPE web and a plain PE sealing web belong to the same polymer family, the finished pack sits at the mono-material end of the spectrum rather than the multi-material end — which is what recycling streams require. For the regulatory background and the difference between recyclability and recycled content, see our mono-material guide.
Convert with us
OLUNRO supplies vacuum metallized polyethylene film for lamination, and runs coating, metallizing, lamination, slitting and bag-making in-house. Our PE film and bag line operates under the Global Recycled Standard (Intertek TE-00352946) with per-shipment Transaction Certificates, so recyclability and recycled content can be addressed in the same structure.
If you want to test whether two layers will hold for your product:
Send the current three-layer structure, the contents and the shelf-life target. We will tell you honestly whether two plies will carry it — and if they will not, we will say so.
Contact: info@olunropack.com · +86 532 6776 6956