What is the three-layer co-extrusion process?
Three-layer co-extrusion is a technology that simultaneously extrudes three different plastic pellets through the same die head, allowing them to naturally bond in a molten state to form a multi-layer structure.
Core Advantages
- Each layer can be independently designed (barrier layer, strength layer, heat-seal layer)
- No adhesive required between layers, eco-friendly with no solvent residue
- Thickness tolerance can be controlled within ±0.01mm.
- High production efficiency, suitable for large-volume industrial orders
Typical Layer Structure Configuration
| Hierarchy | Common Materials | Features |
|---|---|---|
| Outer Layer (Printing Layer) | PET / PA / PP | Provide printability and abrasion resistance |
| Middle Layer (Barrier Layer) | EVOH / PA / Al | Barrier against oxygen, water vapor, and odors |
| Inner Layer (Heat-Seal Layer) | PE / EVA / mLLDPE | Provide heat seal strength and puncture resistance |
Critical Process Parameters
1. Temperature Control
Each layer has a different melting temperature and requires precise control: PET (260-280°C), PA (220-250°C), PE (160-200°C)
2. Thickness Ratio
Typical ratio:30% / 20% / 50%(Outer/Middle/Inner)
Performance Testing Methods
- Tensile Strength：GB/T 1040.3，≥ 25 MPa
- Oxygen Transmission Rate：GB/T 19789，≤ 100 cm³/(m²·d·atm)
- Sealing Strength：QB/T 2358，≥ 15 N/15mm
How to choose the right three-layer co-extruded roll film?
Purchase RecommendationsClarify the properties of the contents, confirm the heat sealing conditions, pay attention to thickness tolerance, and require the provision of test reports.
Conclusion
The three-layer co-extrusion roll film process, with its outstanding performance and environmental benefits, has become a technological benchmark in the packaging industry.