Production of EVA via the High-Pressure Tubular Process

In the rapidly evolving landscape of polymer engineering, Ethylene-Vinyl Acetate (EVA) copolymers have emerged as a critical material driving global decarbonization and industrial upgrading. Particularly in the photovoltaic (PV) encapsulation and high-end packaging sectors, the demand for high-quality EVA is skyrocketing. To meet these stringent market requirements, High-Pressure Tubular Reactor Technology has established itself as the gold standard for large-scale, efficient, and high-performance EVA manufacturing.

How Tubular Technology Achieves Precision

Unlike conventional low-pressure polymerizations, EVA synthesis via the tubular route operates under extreme conditions—typically at pressures ranging from 2,000 to over 3,000 bar and temperatures between 150°C and 300°C. The tubular reactor acts as a long, high-pressure jacketed pipe (often exceeding 1 to 2 kilometers in length). The reaction mixture flows at an exceptionally high velocity as a "plug flow," ensuring excellent heat transfer through the reactor walls via cooling water jackets. Polymerization is initiated by injecting organic peroxides at multiple zones along the reactor, enabling tailored macromolecular architecture and continuous control.

Technical Specifications

Based on advanced high-pressure tubular technology, our premium portfolio offers distinct grades with finely tuned Vinyl Acetate (VA) content and Melt Index (MI) configurations, tailored for high-performance industrial applications.

The Photovoltaic & Encapsulation Pillar (28% - 33% VA)

For solar energy applications, polymer cleanliness and optical transparency are non-negotiable. High-pressure tubular grades such as EVA V3315 (HANWHA EVA 1834) and EVA V3345 (boasting a high VA content of 33.0%) along with EVA V2825 (28.0% VA) are tailored specifically for this purpose. 

• Extreme Flexibility: As the VA content reaches 28% to 33%, the crystalline phase of the polyethylene is disrupted. This drops the melting point to a controlled 60°C - 71°C and pushes the ultimate elongation to an astonishing 800% to 900%. 
• Zero-Defect Extrusion: Because the tubular process prevents polymer stagnation, these grades exhibit ultra-low micro-gel (fish-eye) content. This ensures flawless light transmission and eliminates the risk of localized hot-spots or electrical breakdowns in solar panels over their 25-year lifespan.  

The High-Strength & Extrusion Film Pillar (18% - 25% VA)

When applications demand mechanical integrity, structural toughness, and environmental resistance, the crystalline matrix must be preserved. This is where medium-VA tubular grades excel, represented by EVA V5120J (EVATHENE UE629)and EVA V1818 (18.0% VA). 

• Mechanical Superiority: With a lower VA concentration, these grades maintain a higher melting point (80°C - 82°C) and higher hardness (80 - 85 Shore A). Most notably, EVA V5120J delivers a superior tensile strength of 12.0 MPa and a well-balanced melt index of 3.0 g/10min.
• Downstream Versatility: These properties make them the ideal choice for premium agricultural cross-linked films, heavy-duty packaging, and high-end shoe foaming formulations where environmental stress crack resistance (ESCR) is critical.  

Modern tubular installations feature optimized, multi-zone single-pass conversion rates reaching up to 35% - 40%, which is significantly higher than older autoclave alternatives. Beyond product purity, the high-pressure tubular route is a champion of green manufacturing. The massive amount of exothermic reaction heat generated during free-radical polymerization is efficiently captured via the reactor’s cooling jackets. This heat is converted into high-pressure steam and reused to power the plant’s auxiliary systems and high-pressure compressors. This thermal integration drastically lowers the specific energy consumption and carbon footprint per ton of advanced polymer produced.  

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