If you are specifying a flexible packaging film, you will eventually face the same decision: laminated structure or mono-material? The answer is not generic. It depends on your product’s barrier requirements, shelf life targets, filling line setup, retailer obligations, and sustainability position.
This guide is written for buyers and technical managers who need more than a surface-level comparison. We will cover how both film types are actually constructed, what drives their performance, where each one falls short, and how to map film type to specific product requirements.
How Laminated Flexible Packaging Films Are Built
A laminated flexible packaging film is constructed from two or more distinct material layers bonded together, each contributing a specific function the other layers cannot provide alone. The bonding process is either adhesive lamination (using solvent-based or solvent-free adhesives) or extrusion lamination (where a molten polymer is extruded between substrates to bond them on the line).
A standard three-layer food-grade laminate has three functional zones:
Substrate layer (outer): Provides structural rigidity, dimensional stability, and a surface suitable for print.
- Biaxially oriented PET (BOPET) is the most common outer substrate: it is dimensionally stable at elevated temperatures, provides excellent print reproduction for rotogravure and flexographic processes, and resists puncture.
- Oriented polypropylene (OPP) is a lighter and lower-cost alternative used in confectionery, snacks, and applications where print quality requirements are standard rather than premium.
- Oriented nylon (BOPA or PA) is used where flexibility at low temperatures and gas barrier from the substrate itself are needed, common in fresh meat and vacuum pack applications.
Barrier layer (middle): Controls the transmission of oxygen, moisture, light, and aroma through the film. The choice of barrier material dictates the overall performance of the structure:
- Aluminium foil (AL): Provides a near-total barrier to oxygen, moisture, light, and volatile compounds. OTR (oxygen transmission rate) approaches 0 cm3/m2/day. MVTR (moisture vapour transmission rate) is similarly near-zero. Used in retort pouches, coffee packaging requiring long ambient shelf life, pharmaceutical blister backing, and any application demanding complete light exclusion. The trade-off is weight, cost, and the fact that foil-based structures cannot carry an OPRL “Recycle” designation.
- Metallised films (PETMET, VMcPP): A thin vacuum-deposited aluminium layer applied to PET or cast PP film. Provides high barrier at lower weight than foil: OTR typically 0.1 to 1.5 cm3/m2/day, MVTR 0.1 to 0.5 g/m2/day depending on grade and coating weight. Widely used in snack packaging, pet food, and confectionery where a full foil barrier is not required but high barrier performance is. Also useful where metallic visual effect is required.
- EVOH (ethylene vinyl alcohol copolymer): Provides outstanding oxygen barrier, with OTR values as low as 0.1 to 0.5 cm3/m2/day in standard humidity conditions. Unlike foil, it is fully transparent. However, EVOH is moisture-sensitive: its barrier performance degrades significantly at high relative humidity, which is why it is always sandwiched between moisture-resistant PE layers in a co-extruded or laminated structure. Used in fresh meat and seafood, cheese, and ready meal packaging where optical clarity is required alongside high oxygen barrier.
Sealant layer (inner): Bonds the packaging closed during heat sealing on the filling line.
- Cast polypropylene (CPP) is the standard sealant for high-temperature applications, including retort processing (up to 131°C).
- Linear low-density polyethylene (LLDPE) or metallocene LLDPE (mLLDPE) is used for lower-temperature sealing applications and where high hot-tack performance is needed during vertical form-fill-seal (VFFS) or horizontal form-fill-seal (HFFS) operation.
Common laminated film structures and their applications:
| Film Structure | Barrier Level | OTR (indicative) | Typical Application |
|---|---|---|---|
| PET / PETMET / PE | High | 0.5 to 1.5 cm3/m2/day | Snacks, coffee, pet food dry |
| PET / AL / PE | Very high (foil) | Near zero | Retort meals, wet pet food, pharma |
| OPP / metOPP / PE | Medium-high | 1 to 3 cm3/m2/day | Confectionery, biscuits, snacks |
| PET / EVOH / PE | High (clear) | 0.1 to 0.5 cm3/m2/day | Cheese, fresh meat, ready meals |
| PA / PE | Medium | 5 to 15 cm3/m2/day | Fresh meat, vacuum packaging |
| PET / CPP | Standard | 30 to 80 cm3/m2/day | Dry goods, flow wrap, low barrier |
The adhesive chemistry also matters. Solvent-free adhesives are now standard in food-contact applications across the EU and UK, but the specific adhesive grade affects flexibility at low temperatures, chemical resistance, and migration compliance under food contact regulations. For frozen applications, the laminate must retain flexibility and seal integrity at temperatures as low as -40°C, which requires specific adhesive selection.
How Mono-material Flexible Packaging Films Are Built
Mono-material films use a single polymer family throughout the entire structure, making the film recyclable through a single material stream. The two commercial routes are all-PE (polyethylene) and mono-PP (polypropylene).
All-PE structures (BOPE-based): Modern mono-PE films use biaxially oriented polyethylene (BOPE) as the structural outer layer. BOPE is produced by stretching PE film in both the machine and transverse directions, significantly improving stiffness, optical clarity, and print receptivity compared to conventional blown PE.
It behaves more like BOPET than standard PE in terms of machinability, which is a key reason it has become the preferred substrate for high-performance mono-material structures.
The internal structure is built using co-extrusion: multiple layers of different PE grades are combined in a single production step. A typical all-PE structure for food packaging might use HDPE or MDPE for stiffness in the outer layers, a co-extruded EVOH or EVOH-containing core for oxygen barrier, and LLDPE or mLLDPE as the sealant.
The entire structure is PE-based, so it is compatible with LDPE recycling streams (code 4) and qualifies for the OPRL “Recycle” label under the UK soft plastics collection scheme. See our recyclable films range for available formats.
An important sealing consideration: because BOPE and PE sealant layers have overlapping melting ranges, the sealing window (the temperature range within which a consistent, strong seal forms without distorting the film) is narrower than with a CPP sealant on a conventional laminate.
Seal bar temperature, dwell time, and cooling settings may need adjustment when switching from a laminated film to a BOPE-based mono-material structure. This is not a barrier to switching, but it is a variable that should be validated during trials on your filling line before production sign-off.
Mono-PP structures: Built from oriented polypropylene throughout, either as BOPP / CPP / BOPP or as a fully co-extruded PP structure. Mono-PP offers good stiffness, clarity, and reasonable barrier performance. The limitation in the UK context is that the recycling infrastructure for PP films is less developed than for PE.
Most UK supermarket flexible plastic take-back schemes currently collect PE films (LDPE 4), and mono-PP films do not always qualify for the same on-pack “Recycle” claim. For applications targeting UK retail recyclability, all-PE is currently the more robust route.
Print performance on BOPE: Rotogravure and digital print on BOPE has improved substantially. Surface corona treatment and primer selection now enable ink adhesion levels comparable to BOPET in most food packaging applications. High-definition photography and fine text reproduce well.
Metallic effects can be achieved through cold foiling, though the range is narrower than on a metallised laminate. For brands where premium print finish is a hard requirement, BOPE is a viable route; for the most demanding applications, PET-based laminates retain a performance advantage.
Barrier Performance: Where Mono-material Films Currently Stand
The performance gap between high-barrier laminates and mono-material films has narrowed but has not closed. For applications where OTR must be below 0.5 cm3/m2/day, or where moisture barrier at high humidity is critical, laminated structures remain the correct specification.
For products with moderate barrier needs, specifically ambient products with shelf lives up to six months, chilled products, or frozen food applications, a well-engineered BOPE-based film provides adequate protection. Products such as dry snacks, cereals, pet treats, and chilled bakery items are successfully transitioned to mono-material films without shelf life compromise, provided that validation testing is conducted rather than assumptions made.
Recyclability, OPRL and the UK Plastic Packaging Tax
Two UK-specific regulatory factors are now influencing film specification decisions at commercial level:
OPRL (On-Pack Recycling Label): The OPRL scheme governs what the “Recycle” and “Don’t Recycle” labels on UK packaging actually mean. A packaging component can only carry the “Recycle” label if it is collected and genuinely recycled at scale: at least 75% of UK local authorities for kerbside streams, or the equivalent threshold for front-of-store soft plastic collections.
Standard laminated films, including PET/PETMET/PE and all foil-containing structures, do not qualify: they carry “Don’t Recycle.” Mono-PE films that meet OPRL criteria carry “Recycle” under the LDPE 4 soft plastics stream. This distinction matters: major UK retailers including Tesco, Sainsbury’s and M&S embed OPRL compliance into supplier codes of practice, and brands without a credible recyclable packaging route are at a disadvantage in ranging decisions.
UK Plastic Packaging Tax (PPT): The tax applies to packaging manufactured in or imported into the UK that contains less than 30% recycled plastic by weight. The current rate for 2025/26 is £217.85 per tonne. Standard laminated films, which typically contain no post-consumer recycled (PCR) content, are fully taxable.
For a full breakdown of how PPT is calculated and what exemptions apply, see our Plastic Packaging Tax guide.
Choosing Between Laminated and Mono-material: A Decision Framework
Specify a laminated film when:
Your product has an OTR requirement below 1 cm3/m2/day for ambient storage, requires retort processing (above 100°C sterilisation), needs to exclude light (oils, nutraceuticals, UV-sensitive products), has a shelf life of 12 months or more at ambient temperature, or is produced via a hot-fill process.
Laminated films are also appropriate where your route to market does not carry OPRL pressure and the performance case for mono-material has not been validated for your specific product.
Specify a mono-material film when:
Your product has moderate barrier requirements and an achievable shelf life within what the film’s OTR supports. You supply UK retail channels where OPRL compliance is required or expected.
You want to reduce your UK Plastic Packaging Tax exposure. Your packaging contributes to scope 3 emissions commitments and you need to demonstrate measurable CO2 reduction. Examples: dry snacks, ambient cereals, coffee with acceptable OTR margins, frozen food, pet treats, health and beauty products, and chilled fresh products where cold chain controls the shelf life rather than packaging barrier alone.
When you are not sure: run a barrier brief. Provide your product type, target shelf life, storage conditions, and current packaging specification. A competent supplier will be able to model whether a mono-material structure meets your barrier requirement, or identify the gap and quantify the shelf life risk. This takes days, not weeks, and it is the correct starting point before a decision is made.
How Aropack Can Help
Aropack supplies both laminated film structures and the Aropack Mono range of BOPE and mono-PP films. We are not positioned to sell one over the other: the right recommendation depends on your product specification, and we will tell you if a mono-material film is not the right answer for your application.
For laminated film projects, we can specify structures across the full barrier range, provide OTR and MVTR data for any combination, and advise on sealant and adhesive selection for your filling line and application temperature. For mono-material enquiries, we can advise on Aropack Mono options, PCR content levels for PPT documentation, and OPRL labelling accuracy.
If you are switching from laminated to mono-material, we strongly recommend requesting physical samples and conducting filling line and shelf life trials before committing to a production run.
Give us a call on 01233 281460 or send us an email at info@aropack.co.uk for a consultation. Let us help you find the perfect balance between sustainability and functionality.
