From 7-Layer to 9-Layer EVOH Co-Extruded Films: The Premium Choice for High-End Packaging

As the global packaging industry accelerates its shift toward high-performance and sustainable solutions, Evoh material (ethylene-Vinyl Alcohol Copolymer) multilayer co-extruded films are experiencing rapid growth in applications across food, pharmaceutical, and electronic packaging. These films are evolving from being considered a "high-performance option" to becoming an essential material in advanced packaging systems.

Performance Comparison: The “Hardcore” Advantages of 9-Layer Films

1.Barrier Properties: The 9-Layer “Moat”

（1）Oxygen Barrier:

7-layer films typically have an oxygen transmission rate (OTR) of 0.13–0.5 cm³/(m²·day). By integrating dual barrier layers of EVOH polymer and PA, 9-layer films can reduce the OTR to below 0.05 cm³/(m²·day). In food packaging, this significantly extends meat shelf life by over 30%.

（2）Moisture Barrier:

Thanks to symmetrical structures (e.g., PE/EVOH/PE/PA/PE), 9-layer films can achieve water vapor transmission rates (WVTR) as low as 0.5 g/(m²·day)—a 40% improvement over 7-layer films. This makes them ideal for pharmaceutical packaging in high-humidity environments.

2.Mechanical Strength: Top-Tier Puncture and Tear Resistance

（1）Puncture Resistance:

9-layer films can reach puncture strengths of up to 15 N/mm²—25% higher than 7-layer films—effectively resisting sharp objects such as bones or medical instruments, reducing packaging failure rates.

（2）Tensile Strength:

With longitudinal tensile strength up to 40 MPa and transverse tensile strength up to 35 MPa, 9-layer films outperform 7-layer films by 15% and 10% respectively—ideal for high-speed packaging lines.

3.Thermal Stability: A Versatile Performer in Extreme Conditions

（1）High-Temperature Retort:

After retorting at 121°C for 30 minutes, 9-layer films maintain heat seal strength at 8 N/15mm, whereas 7-layer films may drop to 6 N/15mm—suitable for ready-to-eat food sterilization processes.

（2）Low-Temperature Flexibility:

9-layer films remain flexible at -40°C, while 7-layer films may become brittle—critical for packaging of deep-sea seafood and other frozen products.

Material Composition: The “Precision Formulation” of 9-Layer Films

Core Functional Layers:

7-Layer Films: 1 EVOH layer + 2 PA layers

9-Layer Films: 2 EVOH layers + 3 PA layers

EVOH Layer:

The EVOH layer in 9-layer films can be reduced to 3 μm (vs. 5 μm in 7-layer films) while enhancing barrier performance by 50% via a dual EVOH sandwich structure.

PA Layer:

9-layer films use a PA6/PA66 blend, offering 20% higher impact resistance compared to the PA6-only composition in 7-layer films.

Cost Analysis: The “Cost-Performance Paradox” of 9-Layer Films

(1) Unit Price Difference

The unit price of 9-layer films is typically 15%–25% higher than 7-layer films.

For example, 7-layer films are priced around ¥18/kg, while 9-layer films range from ¥21–23/kg.

Thickness Optimization:

9-layer films can be down-gauged (e.g., from 50μm to 40μm), limiting per-square-meter cost increases to only 5%–10% without sacrificing performance.

(2)Long-Term Cost Benefits

Reduced Waste:

Improved puncture resistance lowers packaging damage, potentially reducing overall costs by 8%–12% in food applications.

Operational Efficiency:

Enhanced uniformity allows production line speeds to increase by 20%, reducing energy costs per unit.

(3)Application-Based Premium

In high-end segments such as imported beef and pharmaceuticals, 9-layer films can command a 30%–50% price premium thanks to their superior shelf-life extension and brand-enhancing appearance.

Why Choose 9-Layer? Five Core Application Scenarios

(1) High Barrier Demands:

In pet food packaging, 9-layer films offer 60% lower oxygen transmission than 7-layer films, preventing oil rancidity.

(2)Challenging Environments:

For deep-sea fish oil packaging, 9-layer films retain flexibility at -50°C, while 7-layer films may crack.

(3) High-Speed Packaging:

With superior tensile strength, 9-layer films support line speeds of up to 300 packs/min—ideal for mass production of ready meals.

(4) Sustainability Trends:

9-layer films can be designed with recyclable materials (e.g., all-PE structures), whereas PA/EVOH barrier in 7-layer films faces environmental recycling challenges (source: Finance Industry).

(5) Premium Branding:

With haze below 2% and gloss over 80 (at 45°), 9-layer films enhance product aesthetics and appeal to premium consumers (Jintai News).

Through refined material distribution and structural innovation, 9-layer co-extruded films outperform 7-layer alternatives in barrier properties, mechanical strength, and thermal stability. While initial costs are higher, their superior performance, efficiency gains, and added value in premium markets make them a strategic choice for companies aiming to enhance their competitive edge.