Demands for sustainability and higher shelf life in packaging are pushing the film industry in two directions – towards biodegradable barrier films and to long-life films that extend product life and reduce waste. The latest materials and technology will be discussed at the AMI’s conference, Multilayer Packaging Films 2010, from June 15-16, 2010 at New Jersey.
At the 2009 conference held in Germany in November, Andrew Reynolds, Research Director at Applied Market Information, reviewed the industry trends for flexible packaging, which constitutes 42% of the plastics packaging market. Polyethylene film makes up 40% of this, with BOPP at 20%. It is a growing market and is benefiting from lifestyle and demographic changes, for example, an increase in ready meals for working families. Okopet Consulting outlined the uses of each type of multilayer film: for example, LDPE combinations are used in flow packs for meat, cheese, coffee, ketchup and hygiene. Laminated film such as OPA/PE is used for cheese. BOPP laminates are used in applications such as labels for bottles, ice cream, chips, confectionery, bakery goods, salted snacks and tea. PET combinations provide aroma-proofing. Factors to consider include steamability, sealing, barrier (such as modified atmosphere (MAP) or controlled atmosphere packaging), microwaveability, etc., depending on the end use. In Slovakia there is one producer of multilayer film, Terichem. In Hungary these include Pannunion and Ongropack.
Biaxplen manufactures 9-layer coextruded barrier films in Russia. Materials are selected for permeability: PLA has high water vapour permeability and HDPE has the lowest; whereas for oxygen permeability, LDPE is very permeable, and EVOH offers the best barrier. Film for fresh bakery products has relatively high oxygen and water permeability so PLA can be used, whereas baby food and coffee need a high barrier product. Cost is a big factor in film manufacture, driving the company’s move to one-step multilayer coextrusion.
The US Army Natick Soldier Research Development and Engineering Center has been developing a high barrier non-foil system for army rations that is retortable and recyclable. It requires a shelf-life of 3 years at 27C. There is a move away from foil, which can develop pinholes and stress cracks. It has been working with EVOH from Kuraray America, PP from Flint Hills, polyamide from Honeywell, and tie resins from Mitsui Chemicals America. The PP forms the external layers, then tie layers with EVOH or EVOH and two PA layers in the middle. It is also investigating HDPE as a barrier layer.
In Turkey, Superfilm Ambalaj has 3 BOPP lines, 1 BOPET line and 1 cast barrier line (7 layers). The cast film is being used for trays, lidding, bags, medical and food packaging. New products include BOPP/Al foil/CPP for stand up pouches and BOPET/metallised BOPET/PE for shampoo. The company is also working on oxo-degradable PP film.
The Italian producer of BOPP film, Taghleef Industries, illustrated the good moisture barrier properties of BOPP compared to PET and OPA. The BOPP in D701 is coextruded with a high gas barrier layer and is heat sealable on both sides, so it could replace coated films and have new applications in MAP. Applications include pasta, coffee and sliced meat packaging.
Constantia Flexibles has developed a new multilayer lid structure, which can be laser cut for easy opening. The Chocomel Hot lid won a Worldstar Packaging Award: in the Netherlands the Senseo machine dominates, so Friesland wanted a drink package that would fit the existing machines with lids at both ends.
Norner Innovation provides technical support to the packaging industry. It has studied the LLDPE from different suppliers for properties such as melting behavior and Vicat softening termperature. It has also assisted in packaging for ready rolled pizza dough (PET/adhesive/LDPE/EVOH/LLDPE) and grated cheese (PE/adhesive/PET/adhesive/PP).
Base polymers can be modified to improve properties. DuPont de Nemours has blended EVOH with polyamide to improve properties such as thermoformability and retort shock resistance. EVOH can also be blended with the PA ionomer Surlyn™: the material is softer, stretches better, and this can also cut costs. DuPont also has concentrates of highly functionalized adhesive resins, which can be blended into PE and PP resins for use as a tie layer. Ube Engineering Plastics provides materials such as copolyamides (with a lower degree of crystallization) for multilayer packaging and has tested it on applications such as sausage casings and shrink bags.
Gary Oliver of Extrusion Dies Industries gave the top scoring paper at Multilayer Packaging Films 2009. He described layer multiplication devices to provide the proper pressure drops and balanced flow polymer channels, considering individual material viscosity and rheology. The company also checked end properties such as oxygen transmission rates.
Film extrusion technology is provided by companies such as Macchi, which is conscious of the need to cut costs, for example by down gauging. Reifenhauser Keifel Extrusion has looked at processor trends such as smaller lot sizes, entailing fast purging times and high line flexibility. It has a 7-layer horizontal distribution system that permits individual temperature settings for each layer. Web gauging technology is supplied by Thermo Fisher Scientific; it takes measurements of double lay-flat film after collapsing the bubble.
The hot topic is compostable packaging. The Ceramis unit of Alcan Packaging Kreuzlingen has been working on barrier biodegradable PLA packaging films. The Ceramis process involves coating with a silicon oxide nanobarrier layer using electron beam evaporation and the challenge is the low heat resistance of PLA (the coating is applied at 1520C). The PLA-SiOx film is biodegradable, compostable, high barrier and transparent. Novamont has tested its biodegradable material, Mater-Bi, in extrusion coating and lamination on standard film processing equipment.
Legislation is extensive for food packaging. Keller and Heckman have examined the implications of the new EU Active and Intelligent Packaging Regulation 450/2009. This new law applies to items such as oxygen scavengers: the definition is packaging “designed to deliberately incorporate components that release or absorb substances from or into the packaged food or its surrounding environment”. One common example is iron oxide used for oxygen absorption. Antimicrobials “intended to migrate from packaging to the food” are also included. Many packaging materials are decorated with inks, and the Flint Group is one supplier. They also have expertise in the safety and legislative aspects with regard to food packaging, where the EU has a particular focus. Multilayer Packaging Films 2010 provides a unique opportunity to study the latest market trends and technologies.