Multilayer Packaging Films 2007 Conference

Technology for new multilayer film lines is improving and material combinations are being developed to give high quality packaging film with outstanding performance. The property requirements for packaging can be very demanding. Food packaging applications require high barrier properties to extend the shelf-life of dairy and meat products, among others. Films may need to act as a barrier or be permeable to moisture and oxygen. They need to provide an effective protective layer against external chemicals whilst preserving factors such as flavour, fragrance and colour. Anti-UV properties may also be a pre-requisite, either to protect the film itself or its contents from light. Heatable food packaging and medical products may have a long shelf-life and need to withstand high heat, or be microwaveable and sterilizable. Add to this impact strength and puncture resistance to protect the package contents from damage in transit and it is evident that the specifications for films can be extremely high. Packaging helps to sell the product and special effects can be incorporated to enhance the gloss, to add colour or give an iridescent shimmer. Films are generally transparent, a property that needs to be considered when combining several layers. Many products are labelled or decorated in some way, so the outer layer of film must be printable and/or withstand adhesives and solvents from the labelling process. Multilayer films combine materials and additives with different properties to meet all of the specifications for each packaging application. The most common materials in use are the polyolefins, PE and PP including BOPP. Metallization can also provide some of the extra property requirements. Bonding technology is used to effectively combine different materials, which may involve adding extra adhesive interlayers. Flexibility is a primary requirement of film. Nylon is being added to enhance barrier properties, but if the layer is too thick this can make the film stiffer. This can be overcome by using several thinner layers of this more expensive material giving up to 9-layers. As thinner layers have been introduced it has permitted the use of other engineering plastics such as PET, because the material costs can be kept down. Nanocomposites of nylon 6, polyester and PP are also coming into use in multilayer packaging, because of their excellent barrier properties. The processing technology involved in multilayer film production includes coextrusion blowing, multilayer casting, lamination, metallizing and coating. Complications of multilayer film production include processing several different materials at once with different rheological properties and cooling rates, care has to be taken to ensure consistent layer thickness and to avoid delamination. It can also take some time to purge equipment after use. Gauging the film thickness accurately can help to cut material costs and assist with quality control. Regulations affecting any aspect of the packaging industry will also apply to multilayer films, such as food contact safety testing and recycling. A Press Release on International Conference 27-29 March 2007, Maritim Hotel, Cologne, Germany