Complex laminated film: understand the structure to choose the right layer

When looking at a bag of roasted coffee or a snack bag on a supermarket shelf, you are looking at a structure made up of multiple layers of adhesive films stacked on top of each other, not a single plastic sheet. Each layer addresses a specific issue that no other layer can replace. Understanding this helps you know what structure you need and not pay for unnecessary layers.

Complex composite film what is it

Composite film (laminated multilayer film) is a flexible packaging material made up of multiple layers of film bonded together with specialized adhesives. The most common layer combination for food packaging consists of three main components: PET (polyethylene terephthalate) on the outermost layer, a barrier layer in the middle, and PE (polyethylene) on the innermost layer.

The role of each layer is clearly defined. The outer PET layer is for printing, providing mechanical strength and scratch resistance. The middle barrier layer prevents oxygen, moisture, and light from penetrating the product. The inner PE layer seals the package with heat during the packaging process.

The middle barrier layer has two distinct types that need to be clearly differentiated. VMPET is a PET film coated with vacuum aluminum, with a very thin aluminum layer that effectively blocks moisture and gases but does not achieve absolute levels and may have small pinholes. Real aluminum foil is an actual metal sheet, providing almost zero oxygen and moisture barrier, and nearly absolute light blocking. These are two different levels of barriers, not one.

The laminated surface can be matte or glossy depending on brand requirements. The final product can be a stand-up pouch with a zipper, a four-seal pouch, a pillow bag, or other shaped forms depending on the manufacturer's packaging machine.

When to choose, when not to

Laminated film is the right answer when barrier properties, meaning moisture and gas resistance, are the top priority for the product. Specifically, here are the suitable situations.

• Oxygen and moisture-sensitive products that need to retain aroma: freshly roasted coffee, cashews, granola, protein powder, nutritional powder.
• Need self-standing bags on shelves with zippers for customers to open and close.
• Do you need lightweight, soft packaging with low unit costs for large print runs?
• Light-sensitive products require a high light barrier; use structures with real aluminum foil.
• Single-use sealed packaging for wet cosmetic masks or food samples.

Conversely, there are situations where patching is not the right choice.

If your brand prioritizes recycling or green commitments, multi-layer laminates are not the way to go, unless you switch to a mono-material structure and accept trade-offs regarding barrier properties. If you need to test the market with a small batch, the initial costs for printing cylinders and bag molds will make the unit price unreasonable.

Costs, time and quantity

The cost of laminated film consists of two separate parts. The initial cost includes making the gravure printing cylinder or flexo printing plate and the bag die if needed; this is a fixed amount spread over the output. The unit cost per bag is low when the output is large enough, but unreasonably high for small batches.

The structure using real aluminum foil has a higher film cost than the structure using VMPET, but offers significantly better barrier properties. This difference needs to be balanced with the actual shelf life requirements of the product.

Sinh Vũ acts as the creative director: designing the structure of the bag, surface graphics, and preparing print-ready files for the film printer. Sinh Vũ does not guarantee printing prices as that is a direct negotiation between you and the film printer, fluctuating based on quantity, layer structure, and order timing.

Note: food contact films in Vietnam fall under QCVN 12-1:2011/BYT of the Ministry of Health. The supplier of the film must provide documentation for the PE layer that meets food contact standards. Sinh Vũ will remind you to request this documentation when working with the printer.

What does Sinh Vũ need from you to get started

For Sinh Vũ to advise on the correct layer structure and create a standard design file, you need to provide the following information.

• Specific product and sensitivity levels to oxygen and moisture: what is the desired shelf life and what are the storage conditions?
• Distribution and market channels: domestic supermarkets, exports, or online sales, as they affect label requirements and compliance standards.
• The number of SKUs (distinct goods) and the expected quantity for each print run.
• A framework budget for the design part and the target unit price of packaging you are aiming for.
• The timeline requires finished products to calculate a reasonable backward timeline.
• Special requirements if any: one-way air valve, zipper, product visibility window, or export compliance information.

From the information above, Sinh Vũ will recommend an appropriate layer structure, clearly distinguishing between VMPET and real aluminum so that you do not pay for a barrier higher than necessary, or conversely, do not choose a structure lacking barrier when the product truly needs it. The next step is to send your requirements for Sinh Vũ to schedule a detailed discussion.