CRASH COURSE: LAMINATES AND FILMS
Packaging laminates and films preserve, protect, and enhance the shelf life of various products.
To generalize, they are multiple layers of materials bonded together to create a barrier against external elements like moisture, light and oxygen, ensuring product integrity and extending shelf life.
Materials Used to construct Packaging Laminates and Films
1. Base Films:
Polyethylene (PE): Known for its flexibility and moisture resistance, PE is commonly used in food packaging.
Polypropylene (PP): Offers excellent clarity and heat resistance, making it suitable for applications such as snack packaging.
Polyester (PET): Combines strength with transparency, often used in beverage and food packaging.
Aluminum: Adds a metallic layer for enhanced barrier properties against light, oxygen, and moisture.
2. Adhesive Layers:
Adhesives play a critical role in bonding different layers of films together. They ensure the integrity of the laminate structure.
3. Surface Coatings:
Printable Coatings: Facilitate vibrant and high-quality printing for branding and product information.
Barrier Coatings: Further improve resistance to gases, moisture, and odors.
Key Properties
1. Moisture Barrier: Commonly achieved through the use of moisture-resistant films like polyethylene and specialized coatings.
2. Oxygen Barrier: Materials like aluminum and ethylene vinyl alcohol (EVOH) are employed to create effective oxygen barriers.
3. Light Barrier: Aluminum and opaque films are often incorporated to provide excellent light barrier properties.
These shield products from harmful UV rays, which can cause color fading.
4. Aroma and Flavor Barrier: Specialized barrier coatings, such as those containing aluminum or polyvinylidene chloride (PVdC), are utilized.
They prevent both the escape or entry of odors, preserving the original aroma and flavor of the packaged product.
5. Temperature Barrier: Some packaging laminates are designed to withstand high temperatures, making them suitable for retort pouches used in cooking or sterilization processes.
6. Tear and Puncture Resistance:
Ensures the packaging can withstand the rigors of transportation and handling, preventing accidental damage.
Manufacturing Processes
1. Extrusion Coating: A molten layer of polymer is applied onto a substrate, forming a base film with desirable properties.
2. Lamination: Different films are bonded together using adhesives under heat and pressure, creating a multi-layered structure with enhanced properties.
3. Coating and Metallization: Specialized coatings and metallic layers are applied to achieve specific barriers and aesthetic characteristics.
