The Packaging Community has undertaken a survey into decision making in packaging across 9 European countries and concluded that there is a big move towards environmentally-friendly and sustainable products. This is partly met in the trend towards lower weight, as discussed at the October 2009 AMI conference on Thin Wall Packaging held in Cologne, Germany. Jon Nash of AMI described typical applications: yoghurt, cheese, cream, fresh produce, bakery, yellow fats, ready meals, sandwiches, pet foods, frozen foods, etc. Dairy is the largest sector at almost 25% and chilled meals are among the fastest growing areas. PP and PS dominate, followed by PET and PVC with a small percentage of other materials.
Research conducted by Faerch Plast shows that there is interest in the food industry in moving from cans and glass into plastics. In 2008 it produced 1.7 billion thermoformed trays. Ready meal packaging is produced from CPET and PP; and fresh meat trays from PP, APET, PS, or AMPET®; with cold food and snack bowls from APET, PLA, PS or PP. The company has developed modified high barrier CPET (AMPET®) containers with excellent organoleptic properties, low migration, withstands 130-135C retort, can be reheated in oven and microwave, with easy opening and cost effective. It is being used for long shelf-life products such as Larsen Danish Seafood: mackerel in tomato sauce can be stored for 2 years with a high barrier aluminium coated lidding film. Superfos Deutschland is Europe’s largest injection moulder of packaging, making 3,100 containers per minute. It also offers containers with shelf life of up to 2 years, using PP with a membrane and barrier in-mould label (IML).
Kraft Foods has manufactured 27% lighter weight PP cups by conversion from injection moulding to thermoforming. The products were tested using ASTM D-4169 for factors such as gas and light transmission, drop impact and top load strength. Dairy products require UV barrier which is generally provided using calcium carbonate or titanium dioxide fillers. Another property that is tested is “oil canning”, which occurs when containers are hot-filled and bulge at the base leading to a “rocker bottom”. Overall the performance was fit for purpose: drop impact and hoop strength were improved, while top load, oil canning resistance and light transmission were reduced but still adequate.
Anson Packaging supplies around 15% of the UK thermoformed food packaging market and is folowing the Courtauld Agreement to reduce packaging by 10%. Current materials are PP, PET and PS. Recycled PET is now an option (rPET) and improves the carbon footprint. The company has also moved to punch and die technology which has reduced straight sided pots from 11.3g to 9.0g, and round pots from 10.5g to 9.4g. Illig Maschinenbau produces thermoforming machines and claims to have cut material and energy consumption compared to injection moulding. Production rates have increased and the machines will also handle new materials such as PLA. Kiefel supplies thermoforming machines with a level of computer aided controls.
Norner Innovation has worked to improve the barrier properties of injection moulded containers using multilayer structures. In terms of oxygen permeability, EVOH, PVDC and polyamide are high barrier and are often combined with lower barrier materials to improve properties, requiring a tie layer due to poor adhesion. Norner Innovation has worked to avoid the adhesion layer by modifying the polymers – two-material injection moulding is easier than three. The IML can also be used as a barrier, as can a silicon oxide coating. Netstal-Maschinen supplies IML systems and has commented that the label permit an even thinner wall as it provides an insulation layer and extra rigidity.
There are improved grades of PP from Dow Europe. The high melt flow rate reduces cycle times, enables a lower injection temperature, and allows a thinner wall, while reducing overall energy consumption. The company has also studied organoleptic properties and generated improvements by using a low odour catalyst, careful additive selection, zero or limited peroxide treatment and UNIPOL™ process technology. The material has been tested in transparent thin wall thermoforming and opaque thin wall injection moulding. Dow has also developed foamed sheet for thermoforming, allowing up to 25% light-weighting of polyolefins.
SABIC Europe has also developed improved PP with high flow and good impact/stiffness, improving energy efficiency. The CLEARPACT range can be injection moulded for applications such as transparent ice cream, soup and ready meals. It can also be extrusion-thermoformed for meat, fish, poultry, convenience and frozen food packaging. Milliken supplies clarifiers for PP including sorbitol, which has high clarity and good organoleptics. The company’s nonitol technology gives PP the look and transparency of PS. Its nucleating agents help improve the balance of stiffness and impact properties, and the latest product is food contact approved and focused on thermoforming and injection moulding applications.
RPC Containers is a European market leader and worked with EVAL Europe and Ciba to produce a new PP/EVOH/PP barrier tray containing an oxygen scavenger for retort applications. (Albis has now bought the Ciba oxygen scavenger.) The PP provides retort stability and the EVOH supplies the barrier properties. The scavenger supports the EVOH as a barrier during retort shock, when the molecular structure becomes more permeable.
One alternative to conventional polymers is bioplastics from companies such as Novamont. The material has been injection moulded for use in vending cups, foamed food trays and coffee capsules.
BASF supplies PS for packaging – one target is non-carbonated beverages. Around 0.93 million tons of PS is used in thin wall packaging in Europe. It has a lower cycle time and better properties than PET so less material is required. It can be processed on existing injection moulding and stretch blow moulding machinery. PS has been used in bottles for foods such as yoghurt drinks by companies such as Andechser Molkerei and Schwaelbchen Molkerei. Total Petrochemicals is another supplier and also a member of the European PS Producers Association. Around 46% of PS is used in packaging in Europe. End-of-life management in Europe varies with national programmes. The material can be recycled up to 20 times. There are several PS cup recyclers: Stichting Disposable Benelux, Save-A-Cup (UK) and Eco-collector (France and Benelux). The material can be used in a sandwich layer with virgin materials once approved. It can also be used in non-food applications like CD boxes, plastic benches, coat hangers, etc. it is also has a high calorific value in energy recovery by waste incineration.
The Deutsche Gesellschaft fuer Kunststoff-Recycling takes sorted bales of plastics for recycling. In Germany lightweight packaging is collected in yellow bins and subjected to semi-automatic sorting with an air classifier separating films, large plastic items and others. NIR detection can also be used. Post consumer plastics are re-granulated or re-melted and converted to new products. Energy recovery is the other option.
Thin Wall Packaging offers the eco-benefits of light weight and minimalistic packaging, with excellent performance from yoghurt cups to oven-ready meals. The next international AMI conference, Thin Wall Packaging 2010, will be held from 7-9 December 2010 at the Maritim Hotel in Cologne, Germany.