EVOH High-Barrier Film Production Equipment Selection Guide: 4 Core Requirements for 7-Layer Co-Extrusion Lines
Under the dual drivers of consumption upgrading and environmental sustainability demands, the application of high-barrier packaging materials continues to expand across food, pharmaceutical, and new energy sectors. As one of the three major high-barrier resins, ethylene-vinyl alcohol copolymer (EVOH) has become the core barrier material in multilayer co-extrusion films, owing to its exceptional oxygen barrier properties, high transparency, chemical resistance, and eco-friendly recyclability. However, EVOH’s unique processing characteristics impose strict requirements on production equipment.
1.Core EVOH Characteristics and Industry Trends
1.1 Why is EVOH resin the Preferred Choice for High-Barrier Films?
Extreme Barrier Performance
Oxygen Transmission Rate (OTR) ≤ 0.5 cc/(m²·day·atm) (ASTM D3985 standard, based on Soarnol A4412 data from Nippon Gohsei), four orders of magnitude lower than polyethylene (PE).
Sustainable and Recyclable
Supports 30% Post-Consumer Recycled (PCR) content in co-extrusion, in compliance with the EU's 2024 Packaging and Packaging Waste Regulation (PPWR).
Explosive Growth in Cross-Sector Applications
In 2023, EVOH material demand for new energy battery packaging grew by 35%. CATL adopted EVOH/PA composite films for 4680 battery packaging, achieving a moisture barrier rate of ≤1g/m²·day (according to GB/T 21529 standard).
2.Four Core Equipment Requirements and Key Parameters
2.1 Extruder: The Foundation of Precision Plasticization
Screw Design: Length-to-diameter ratio of 25:1–35:1 and compression ratio of 2.5:1–4:1, ensuring uniform plasticization of EVOH polymer’s high-viscosity melt.
Temperature Control Precision: Segmented temperature control within ±1°C, using PID algorithms and closed-loop cooling to prevent localized overheating and molecular chain degradation.
Extrusion Stability: Servo motor-driven screws with rotational speed fluctuation ≤±1 rpm, ensuring barrier layer thickness deviation <0.015 mm (compliant with ISO 13849-1 safety standards, compatible with high-viscosity grades like BASF’s EVAL H171B).
2.2 Die Head: The Core of Layer Precision
Flow Channel Optimization: Use of coat-hanger die heads with mirror-polished flow channels (Ra≤0.2μm) to minimize melt stagnation and shear heat accumulation.
Layer Ratio Control: Metering pumps combined with pressure sensors for EVOH layer ratio accuracy within ±1%, meeting the demands of premium packaging applications.
Corrosion Resistance: Die head interiors plated with hard chrome or made from nickel-based alloys to resist acidic by-products during EVOH processing.
2.3 Cooling System: Ensuring Film Performance and Formation
High-Efficiency Cooling: Coordinated air cooling (15–30°C) and water cooling (10–20°C) systems, achieving a cooling rate of ≥80°C/s (referenced from Kuraray’s 2023 EVOH Processing White Paper).
Uniform Cooling: Multi-zone air knives and annular water curtain designs ensure lateral temperature variations ≤2°C, preventing warpage and uneven thickness.
2.4 Control System: Enabling Smart Manufacturing
Fully Automated Process Control: Integrated PLC+HMI systems monitoring over 200 parameters in real time (temperature, pressure, flow rate, etc.), with automatic deviation correction functions.
3.2024 Industry Frontiers and Compliance Upgrades
3.1 Bio-Based EVOH: A Core Pathway to Carbon Neutrality
Bio EVOH™ by Mitsubishi Chemical: Reduces carbon footprint by 60%, requiring equipment compatibility with dual raw materials (bio-based and petroleum-based) to prevent cross-contamination.
EU REACH Certification: From 2024, packaging materials must contain ≥15% bio-based content to comply.
3.2 Intelligent Manufacturing: New Engine for Cost Reduction and Efficiency
Digital Twin Technology: Virtual debugging enables process optimization within 48 hours, reducing pilot production cycles from 14 days to 7 days (based on Tesla supply chain case studies).
AI Quality Inspection: Compared to traditional manual inspection, AI systems like Lynuc’s DefectGuard™ reduced false defect rates from 15% to 0.3%, saving over RMB 2 million per production line annually (Source: Lynuc 2023 Annual Report).
3.3 Multifunctional Composite Capabilities
Ultrathin EVOH Layer Requirements: Equipment must support precision extrusion of EVOH layers ≤3μm, catering to emerging applications such as solid-state battery aluminum-plastic films. CATL has adopted EVOH/PA composite membranes for 4680 battery packaging, achieving a moisture barrier rate of ≤1g/m²·day (GB/T 21529 standard).
The processing of EVOH plastic represents both a technical challenge and a golden opportunity for industrial upgrading. Choosing equipment specifically adapted for EVOH granules not only ensures product performance but also enables businesses to seize early advantages in trillion-level markets like high-barrier packaging and new energy materials.