Lamination Films

For many applications in flexible packaging, the use of a single material may not satisfy all of the properties demanded of the product. In these cases, a composite consisting of two or more layers of material may provide the desired performance. A particularly common means of creating such a composite is to laminate various polymeric films to other films, foils, papers, etc. with a polymeric adhesive.

The physical and chemical characteristics of the substrate itself will influence the choice of adhesive and coating method to be employed. The substrates that are used in the manufacture of flexible packaging fall into three main categories: papers, foils, and films. By far films are becoming the dominant material because of their lightweight, strength, disposal, and cost characteristics.

This production solution is commonly employed in the packaging industry where the end-products require multi-functional properties, such as high tensile strength and high gas permeability. These are generally referred to as barrier films. The laminate construction can become rather complicated due to the nature of the specific application. A typical laminate used in the medical packaging industry, for example, may be multi-layer composite containing films of polyester / polyethylene / metal foil / polyethylene.

The variety of modern flexible packaging products that are available today would not be possible without modern adhesive systems. The evolution of the packaging industry has closely matched the development of new adhesive materials and production processes. These trends have led to high quality and technically demanding packaging structures required by the consumer.

The design of a multi layer film structure is based on:

1. The film / product compatibility.

2. The lamination process.

3. Machinability on the packaging line.

4. Heat seal characteristics that matches the requirements of the packaging line.

5. Storage (Shelf life ), handling and transportation conditions.

The Flexible Packaging Industry uses multi layer polyethylene and co-polymer films for laminating to one or more substrates, such as polyester film, polypropylene film, often in combinations with Aluminium foil and/or paper, depending upon the packaging system. The multi layer film forms the inner most layer – the Heat Seal Layer – of the laminate, which is in contact with the product. In a multi layer film the polymer, the equipment and the process variables combined, determine the level of crystallinity and orientation and in turn the resulting film properties.