Metallized PE for recyclable mono-material structures
A PET print web, an aluminium foil and a PE sealant make a strong pack and a poor recycling story. Replace the foil with a metallized PE layer and the structure can stay in one polymer. Here is what a mono-material solution buys, and what it costs.
Technical note · Mono-material PE · 5 min read
1. Why a PET/Al/PE laminate does not recycle
The default high-barrier pouch is a three-material sandwich: PET outside to print, aluminium foil in the middle for barrier, PE inside to seal. The problem is the word "and". Recycling sorts by polymer. PET and PE melt at different temperatures and are reprocessed on different lines; foil is neither of them. The adhesive is built to hold, not to come apart, and at packaging scale the layers are not separated again. A foil laminate that a collection scheme accepts usually goes to energy recovery; a stricter one leaves it as residue. The barrier was never the problem — the number of materials in the structure was.
2. What changes when the pack stays in PE
A mono-material PE structure keeps one polymer family and puts the barrier inside it. The print web is PE, reverse-printed; the sealant is PE; the barrier is aluminium vacuum-deposited onto one face of a PE web, tens of nanometres thick.
That layer is a surface treatment, not a second film. The aluminium accounts for a fraction of a micron on the polymer the pack is already made of, so the pack sorts by polymer, washes and is regranulated as PE — provided ink and adhesive do not pull it out of the stream again.
That is why we do not call a film "recyclable" on its own: a mono-material claim is a claim about the finished structure, and the converter decides the rest.
3. Two grades, two jobs
Metallized PE comes in two grades. Both are PE with a metallized face; the difference is which face has to work next.
VMCPE — the sealant grade
Metal on one face, high seal strength on the other. One web carries the barrier and closes the pack, so the structure drops from three layers to two: reverse-printed PE / adhesive / VMCPE. That replaces the traditional reverse-printed / adhesive / barrier / adhesive / sealant stack, and it is the grade for VFFS and HFFS lines and for stand-up and peg-display pouches.
VMNCPE — the high-barrier core grade
VMNCPE does not seal. It goes into the middle of a three-layer PE structure: printed PE / adhesive / VMNCPE / adhesive / PE sealant. It is built for dry or solvent-free lamination, and after lamination its oxygen barrier beats the original single film.
The choice follows the structure: if no web seals yet, VMCPE can be the inner web and one lamination disappears; if a PE sealant is already there, VMNCPE goes in the middle.
4. The numbers, per grade
Barrier and gauge as supplied, not as a finished laminate.
| Property | VMCPE (sealant grade) | VMNCPE (barrier core grade) |
|---|---|---|
| Oxygen transmission (OTR) | ≤ 80 | ≤ 1 |
| Water vapour transmission (WVTR) | 2.1 | ≤ 1 |
| Thickness | 40 µm standard · 50–80 µm made to order | 40–100 µm, quoted per order |
| Heat seal | Yes, one face | No — core layer only |
| Where the barrier sits | Inner web, seal side | Middle of the laminate |
5. What a metallized PE does not do
It is opaque. The metal layer reflects, so the pack reads silver. Where the product has to be visible, the barrier has to be transparent — an AlOx film on BOPP or PET, not this one.
It is not a foil. A metallized layer is nanometres thin and carries grain boundaries and pinholes; foil is a solid metal web. Where a shelf life depends on an absolute barrier, metallized PE is not the substitute.
The barrier is the top few nanometres. A crease, a scuff or a scratched face takes it away. Keep the metallized face on the product side, reduce idler contact, and measure the barrier of the finished pack. If the job is rough, bury the layer: VMNCPE in the middle of a laminate is protected by a web on each side.
The contents decide. Acidic, alkaline, spicy, high-fat, alcoholic or preservative-heavy contents need a trial on the finished structure before production.
6. Before you freeze the structure
- Count the polymers. If a PET or BOPP web is still in the structure, the pack is not mono-material, whatever the barrier does.
- Decide whether a web has to seal. Two-layer with VMCPE as the inner web; three-layer with VMNCPE in the middle.
- Name the barrier class. Metallized PE is an upgrade on plain PE, not a foil replacement. If the shelf life needs an absolute barrier, stop.
- Plan the faces. Reverse-print the print web, seal on the high-seal-strength face, and confirm the seal window on your own machine.
- Trial the contents. Acid, alkali, spice, fat, alcohol and active preservatives are the ones that ask for a trial.
- Order the material. VMCPE is 40 µm as standard and 50–80 µm made to order; VMNCPE runs 40–100 µm, quoted per order. Minimum order is 1 pallet, lead time is 10–15 days, and FDA compliance plus an EU 10/2011 migration report are available on request.
Key facts
- A PET/Al/PE pouch is three materials in one web; a PE/PE structure with a metallized layer is one polymer family.
- The metallized layer is a nanometre-scale aluminium deposit on PE, not a second film.
- VMCPE is the sealant grade for a two-layer structure: WVTR 2.1 g/(m²·24h), OTR ≤ 80 cm³/(m²·0.1MPa·24h).
- VMNCPE is the core grade for a three-layer structure: WVTR ≤ 1, OTR ≤ 1; after lamination its oxygen barrier beats the original single film.
- Mono-material is a property of the finished structure, not of the film alone.
Send the structure, not the film name
Tell us the layers you are building — reverse-printed PE / adhesive / VMCPE, or printed PE / VMNCPE / PE sealant — with the width and gauge. We will say what the film settles and what the trial still has to prove. Minimum order is 1 pallet; lead time is 10–15 days.