Here are the key features of this laminated structure:

1. The “Shield & Seal” Synergy
This is the primary reason for laminating these two materials together:

Outer Layer (MetPET) = The Shield: It provides rigidity, heat resistance, and a barrier against light and oxygen.

Inner Layer (PE) = The Seal: It creates a strong, hermetic (airtight) seal when heated by the packaging machine. MetPET cannot be heat-sealed on its own; without the PE layer, you could not form a bag.

2. “Trapped” Metal Protection
In a typical lamination, the PE is adhered to the metallized side of the PET.

Structure: [PET Film] + [Metal Coating] + [Adhesive] + [PE Film]

Feature: This “traps” the fragile aluminum layer between the two plastic films. It prevents the metal from being scratched off during shipping or handling, ensuring the barrier properties remain intact.

3. Superior Barrier Properties
The laminate offers a comprehensive barrier that neither material can achieve effectively alone:

Oxygen Barrier: The MetPET layer blocks oxygen, preventing food spoilage (oxidation). PE alone is very poor at blocking oxygen.

Moisture Barrier: Both layers contribute, but the combination creates a highly effective shield against water vapor, keeping crispy products (like crackers) dry and powdered products (like coffee) from clumping.

Light Blocking: It blocks up to 99% of UV and visible light, protecting light-sensitive ingredients (like fats and oils in nuts or chips) from going rancid.

4. Mechanical Strength & Durability
Puncture Resistance: The PE layer is soft and elastic, which helps absorb shock and prevents the bag from bursting if dropped.

Stiffness & Shelf Presence: The MetPET layer is rigid. This allows the pouch to stand up straight on a shelf without sagging, unlike a simple PE bag which would crumple.

Flex-Crack Resistance: unlike pure Aluminum Foil, which can crack and create pinholes if bent too much, this laminate is flexible and maintains its barrier even when handled roughly.

5. Aesthetic Options
Metallic Look: If left unprinted or printed with transparent inks, the silver background shines through, giving a premium “metallic” look.

Printability: The outer PET surface is very smooth and excellent for high-quality printing (Rotogravure or Flexo), making the text and images look sharp