Spout Pouches and Bag in Box
Solution
Choosing a Laminate Structure
How to pick the film structure for a pouch when shelf life, fill temperature and the product itself all pull in different directions.
Why This Sequence Matters
A pouch is a stack of films, and each layer is there for a reason. Getting the stack wrong is the most expensive mistake in flexible packaging because it shows up months later as a product that oxidised, a seal that opened in the retort or a pack that cracked along a fold. This page explains the layers we work with and what each one buys you, so the structure on your quotation is a decision rather than a default.
Step by step
Each Stage and What Can Go Wrong
- Outer Web
The print has to survive handling and still look right on shelf.
PET as the outer web for print clarity and stiffness. BOPP where clarity and cost matter more than stiffness. - Oxygen and Light Barrier
Oxygen ingress sets the real shelf life, not the sell by date on the artwork.
Aluminium foil for the highest barrier and full light block, VMPET for a lighter metallised barrier, EVOH as a barrier layer inside a coextruded structure where a clear pack is required. - Mechanical Layer
Packs fail at folds and corners long before the film itself fails.
Nylon interlayer for puncture and flex crack resistance, used in structures such as PET/NY/LDPE and PET/AL/NY/RCPP. - Sealant
The seal is the part that has to survive filling, transport and sometimes 121 degrees of retort.
LDPE for ambient and chilled packs, RCPP where the pack is retorted, CPP where heat resistance is needed without a full retort. - Lamination Method
Solvent residue and delamination both come from how the layers were joined.
Dry lamination and solventless lamination each suit different structures. Coextruded films avoid organic solvent residue altogether. - Verification
A structure that reads well on paper still has to run on your line.
Confirm the structure against your filling temperature, sterilisation step and storage cycle before the cylinders are engraved.
Answers
Choosing a Laminate Structure — Questions
Which structure do I need for a retorted product?
An RCPP sealant structure such as PET/AL/NY/RCPP or PET/AL/PET/RCPP. Standard LDPE sealants are not specified for retort.
What is the difference between aluminium foil and VMPET?
Foil gives the highest oxygen and light barrier and full opacity. VMPET is a metallised polyester that gives a lighter barrier at lower cost and lower weight.
When would I use nylon in the structure?
Where the pack is handled, folded or contains something with edges. Nylon adds puncture resistance and flex crack resistance, which is why it appears in PET/NY/LDPE and foil structures.
Can I have a barrier pack that is still transparent?
EVOH is used as a barrier layer of composite film and can be coextruded with polyolefin or polyamide, which keeps the pack clear where foil would not.
Do you supply the food contact documentation?
All materials used in production including film, ink and injections are food grade. Tell us which market documentation you need when you place the order.
What film thickness range do you run?
Documented ranges include 20 to 100 microns on flower sleeve film and 17 to 58 micron on OPP and BOPP bags. The right thickness depends on the format and the pack weight.
Start With the Specification
Send what you know: format, volume, product, colours, quantity, port. We will fill the gaps and quote against it.