Coating EVA Layer on BOPP Film

Coating EVA Layer on BOPP Film: Technology, Applications, and Advantages

Introduction

BOPP films (Biaxially Oriented Polypropylene) are among the most widely used packaging materials due to their excellent mechanical properties, clarity, and cost-effectiveness. However, BOPP lacks certain functional properties such as heat sealability and adhesive compatibility. To overcome these limitations, a thin layer of EVA (Ethylene-Vinyl Acetate) is coated on the BOPP surface—enhancing its performance for advanced packaging applications.

Purpose of Coating EVA on BOPP

Naturally, BOPP films are not heat sealable and do not bond well with other materials. By coating a layer of EVA, the BOPP film gains the following properties:

• Heat sealability

• Improved adhesion for lamination

• Resistance to moisture and oils

• Bonding compatibility with aluminum foil, PET, and other substrates

Methods of EVA Coating on BOPP

1. Extrusion Coating

Molten EVA is applied directly onto the BOPP film using an extrusion system. After extrusion, the coated film passes through a chill roll to achieve a smooth and uniform layer.

✅ Advantages:

• Uniform coating thickness

• High bonding strength

• Ideal for sensitive lamination structures

2. Solvent-based or Water-based Coating

EVA is applied as a solution or emulsion using coating systems like micro gravure or comma roll. The film is then dried in a thermal oven.

✅ Advantages:

• Ultra-thin coating layers

• Lower material consumption

• Suitable for pharmaceutical and specialized applications

Technical Properties of EVA-Coated BOPP

Common Applications

1. Food Packaging
   For products such as chips, biscuits, frozen foods, sandwiches, and dairy.

2. Pharmaceutical Packaging
   EVA improves seal integrity and chemical compatibility for medical products.

3. Multilayer Laminates
   Used in structures like BOPP/EVA/AL or BOPP/EVA/PET for vacuum or barrier packaging.

Benefits

• Reliable sealing at low temperatures

• Enhanced adhesion in thermal lamination

• Better chemical and moisture resistance

• Extended shelf-life for packaged products

Challenges and Technical Considerations

• Precise Temperature Control: Excessive heat may damage the BOPP base film.

• Line Speed Synchronization: Especially important during extrusion coating.

• Coating Thickness Control: Critical for cost optimization and maintaining optical properties.

Conclusion

Coating EVA on BOPP film is a practical and effective solution for enhancing packaging film performance. The resulting structure offers improved sealability, adhesion, and barrier properties, making it suitable for high-demand sectors such as food, pharma, and industrial packaging. With the growing need for multilayer smart films, EVA-coated BOPP is expected to play a vital role in the future of flexible packaging.