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As the name suggests, the seven-layer co-extruded high barrier film is made of seven layers of plastic materials with different functions through co-extrusion technology. This multi-layer structure is designed to take advantage of the unique properties of each material to achieve the best barrier effect. The typical structure of the seven-layer co-extruded film may include PE (polyethylene) as the inner and outer layers to provide mechanical strength and heat sealing; PA (nylon) as a barrier layer to enhance gas barrier ability; EVOH (ethylene-vinyl alcohol copolymer) as a core barrier layer, which has extremely high barrier properties to oxygen and water vapor; and TIE (adhesive layer) to ensure the close bonding between the layers.
Oxygen is the main culprit for food oxidation and deterioration. It can trigger a series of chemical reactions such as fat oxidation and enzymatic browning, resulting in darkening of food color, loss of flavor, and decreased nutritional value. The PA layer in the seven-layer co-extruded film, as a high-performance barrier material, has good barrier properties to oxygen. However, what really makes the seven-layer co-extruded film stand out in terms of oxygen barrier is the EVOH layer. EVOH is a polar polymer with a large number of hydroxyl groups (-OH) in its molecular chain. These hydroxyl groups can form strong hydrogen bonds, thus constructing a compact and stable molecular structure, making it difficult for oxygen molecules to penetrate. Therefore, the barrier performance of the EVOH layer to oxygen is far better than that of the PA layer, becoming the key to preventing food oxidation in the seven-layer co-extruded film.
In addition to oxygen barrier, the EVOH layer in the seven-layer co-extruded film also exhibits excellent water vapor barrier performance. In food packaging, the intrusion of moisture will also accelerate the spoilage process of food, leading to the growth of microorganisms and food spoilage. Due to its compact molecular structure, the EVOH layer can effectively block the penetration of water molecules and keep the inside of the package dry. This feature is especially important for foods that need to be moisture-proof, such as nuts, dried products, and baked goods. Through the water vapor barrier of the EVOH layer, these foods can maintain their original taste and flavor in the package and extend the shelf life.
The seven-layer co-extruded high barrier film is widely used in the field of food packaging, covering multiple categories from ready-to-eat meat products, baked goods, fresh fruits and vegetables to dairy products, condiments, etc. Its unique barrier properties enable these foods to maintain the best taste, color and nutritional value in the package, extend the shelf life and reduce waste.
Extend shelf life: By isolating oxygen and moisture, the seven-layer co-extruded film can significantly extend the shelf life of food, providing greater convenience for food manufacturers and consumers.
Maintain food quality: The barrier of oxygen and moisture helps prevent food from oxidative deterioration and microbial growth, and maintain the original flavor and nutritional value of food.
Improve packaging efficiency: The multi-layer structure of the seven-layer co-extruded film not only has excellent barrier properties, but also has good mechanical strength and heat sealing properties, which is convenient for the operation of automated packaging production lines.
Environmental protection and sustainability: Although the seven-layer co-extruded film performs well in performance, environmental issues cannot be ignored. With the global attention to the treatment of plastic waste, the development of degradable or easily recyclable seven-layer co-extruded film materials has become the future development direction of the industry.
Although the seven-layer co-extruded high barrier film has made remarkable achievements in the field of food preservation, its development still faces many challenges. On the one hand, as consumers pay more and more attention to food quality and safety, the performance requirements for packaging materials are becoming increasingly stringent. How to further improve the barrier performance and environmental protection of the seven-layer co-extruded film has become an urgent problem to be solved in the industry. On the other hand, as the world's attention to plastic pollution deepens, the recycling and reuse of the seven-layer co-extruded film has become a topic that the industry must face.
The development of the seven-layer co-extruded high-barrier film will pay more attention to the innovation of materials and the improvement of environmental protection. By developing new high-performance barrier materials, such as bio-based plastics and degradable plastics, the balance between performance and environmental protection of the seven-layer co-extruded film can be achieved. Strengthen the recycling and reuse of packaging waste and promote the development of the seven-layer co-extruded film in a more green and sustainable direction.
