Aluminized PET Film vs. Aluminum Foil: Which Offers Better Barrier Performance?

In industries ranging from food packaging to aerospace insulation, the choice between aluminized PET film and aluminum foil often hinges on one critical factor: barrier performance. Both materials are renowned for their ability to block moisture, oxygen, and light, but their structural differences lead to distinct advantages and limitations. This article dives deep into their barrier properties, applications, and cost-effectiveness to help you make an informed decision.

Understanding the Materials

1. What is Aluminized PET Film?

Aluminized PET film (or aluminized polyester film) is a flexible polyester substrate coated with a thin layer of aluminum via vacuum metallization. This process creates a lightweight, durable material with reflective and barrier properties. Common variants include aluminized Mylar film (a trade name for polyester film) and composites like aluminised polyester film laminated felt or glass cloth for specialized uses.

Key Properties:

• Thickness: Ranges from 12µm to 50µm, balancing flexibility and strength.

• Barrier Performance: Blocks up to 99% of UV light and offers moderate moisture/oxygen resistance.

• Applications: Flexible packaging, electronics shielding, and thermal insulation.

2. What is Aluminum Foil?

Aluminum foil is a thin sheet of pure aluminum, typically rolled to thicknesses between 6µm and 20µm. Unlike metallized films, it provides a 100% continuous metal barrier but lacks inherent flexibility, making it prone to cracking under stress.

Key Properties:

• Barrier Performance: Near-zero permeability to moisture, oxygen, and light.

• Applications: High-barrier food packaging, pharmaceutical blister packs, and industrial insulation.

Barrier Performance Comparison

1. Moisture Resistance

• Aluminized PET Film: Offers excellent moisture resistance (WVTR <0.5 g/m²/day) due to its metallized layer. However, microscopic pinholes from the metallization process can slightly increase permeability.

• Aluminum Foil: Provides an impermeable barrier (WVTR ≈0 g/m²/day), ideal for long-term moisture-sensitive storage (e.g., dried foods, electronics).

Verdict: Foil wins for absolute moisture blocking, but aluminized PET suffices for most flexible packaging needs.

2. Oxygen Barrier

• Aluminized PET Film: Oxygen transmission rates (OTR) range from 0.5–5 cc/m²/day, depending on aluminum coating density. Hybrid versions with SiO₂ coatings enhance performance.

• Aluminum Foil: Zero oxygen transmission, making it unbeatable for preserving oxidation-prone products (e.g., pharmaceuticals, coffee).

Verdict: Foil is superior, but aluminized PET films with advanced coatings bridge the gap for lightweight applications.

3. Light and UV Protection

• Aluminized PET Film: Reflects 97–99% of UV and visible light, protecting light-sensitive goods (e.g., vitamins, adhesives).

• Aluminum Foil: Blocks 100% of light, crucial for photosensitive chemicals or dark chocolate packaging.

Verdict: Foil provides total light blockage, while aluminized PET offers high reflectivity with flexibility.

4. Flexibility and Durability

• Aluminized PET Film: Highly flexible, resistant to cracking, and compatible with lamination (e.g., aluminised polyester film laminated felt for HVAC systems).

• Aluminum Foil: Fragile under repeated bending; cracks compromise barrier integrity.

Verdict: Aluminized PET excels in dynamic environments.

Cost, Sustainability, and Applications

1. Cost-Effectiveness

• Aluminized PET Film: Lower material and shipping costs due to lightweight nature. Ideal for high-volume, thin-profile packaging.

• Aluminum Foil: Higher raw material costs, but unmatched for premium, long-shelf-life products.

2. Environmental Impact

• Aluminized PET Film: Recyclability depends on local facilities; newer biodegradable metallized films are emerging.

• Aluminum Foil: Fully recyclable, but energy-intensive production.

3. Industry Applications

• Food Packaging:

• Aluminized PET: Snack bags, pouches for coffee or pet food.

• Aluminum Foil: Retort pouches, ready-to-eat meals.

• Electronics:

• Aluminized PET: EMI shielding in cables, flexible circuits.

• Construction:

• Aluminized PET: Reflective roofing barriers (aluminised polyester film glass cloth composites for fire resistance).

Head-to-Head Summary

Conclusion

While aluminum foil remains the gold standard for absolute barrier performance, aluminized PET film offers a versatile, cost-effective alternative for applications demanding flexibility and moderate protection. Your choice ultimately depends on balancing factors like budget, environmental goals, and specific barrier needs.

For tailored solutions, explore Super Tech China’s range of aluminized Mylar film and aluminised polyester film laminated felt designed to meet diverse industrial challenges.