Thermoformed packs and blow moulded bottles are at the epicentre of the plastic packaging debate. Lynda Searby examines how users of these packaging formats can improve their sustainability credentials
Perhaps the most obvious way of making thermoformed food trays more sustainable is to switch to a mono PET material that can – technically at least – be recycled. The problem is that the majority of mono materials used for thermoformed trays require a multi-polymer laminate top web to seal onto the tray, rendering the pack non-recyclable if the top remains on the back after opening.
Fortunately, thermoforming machinery manufacturers are onto this. Multivac, for example, says it has developed a one-polymer pack solution that utilises PET as the only polymer, whilst maintaining the necessary barrier protection to guarantee food shelf life.
This is one solution that Multivac has conceived in response to the drive to reduce use of non-recyclable plastic in packaging, but is by no means the only environmentally-responsive innovation to come out of their German-headquartered company’s R&D.
“As a leading manufacturer of packaging solutions worldwide, it has been one of Multivac’s highest priorities to develop packs that provide maximum product protection whilst using minimum resources. Multivac offers a wide range of packaging concepts which start with the use of mono films and extend right up to paper fibre-based materials,” says Elliot Chrisp, business unit manager for materials at Multivac UK.
The use of recyclable paper fibre based materials for thermoformed trays is another avenue that Multivac has pursued – with success. Its formable paper-based material has been awarded On-Pack Recycling Label (OPRL) status as a widely recyclable material.
Multivac’s PaperBoard solution can be used to produce MAP and vacuum skin packs from paper fibre-based materials on standard machines. By using different functional layers, Multivac has managed to produce packs that also meet the barrier requirements demanded by the food industry. The packs can be designed in such a way that the end user is able to separate the cardboard backing from the plastic barrier layer for recycling.
This concept was recently shown at the IFFA trade show in Frankfurt, where flat vacuum skin packs were produced on an R 105 MultiFresh thermoforming machine from reel-fed cardboard composites. Multivac also offers a retrofit solution that can be fitted to producers’ existing equipment to enable them to run paper-based and other alternative forming materials.
Multivac is not alone in having conceived thermoformed packaging concepts that minimise plastic content. Competitor GEA says its current main priority is reducing the amount of plastic used – a focus that has yielded the GEA Food Tray. Combining cardboard and plastic that can be separated for recycling, this concept is said to reduce the amount of plastic used by up to 80%.
Bottom flex film is formed into pre-made corrugated cardboard boxes and spot sealed to the upper area of the carton trays by means of heatable plugs. After filling, evacuating and gassing the pack, the top film is sealed to the bottom film. The result, says GEA, is an ecologically sustainable package with a depth of 20 to 60mm. Similarly, Ulma Packaging has developed LeafSkin packaging as part of its #ULMAweCare sustainability project, a plan designed around reducing plastic waste while maintaining the quality of food produce.
“This project has seen Ulma invest heavily in R&D, which has resulted in the creation of several new types of packaging such as LeafSkin and ReducedScrap. Additionally, many of our thermoformer machines, including the TFS 200 MSV and the TFS 407 R, have been designed to deliver significant reductions in film usage while maintaining high levels of productivity,” says Alistair Cook, product manager at Ulma Packaging UK.
Based on a recyclable flat cardboard tray, LeafSkin is said to reduce film usage by up to 80%. ReducedScrap, meanwhile, is a packaging option that is said to provide a reduction of up to 40% in the plastic needed to package meat products by creating a vacuum through specially designed air holes in the bottom film. On the face of it, such concepts might appear simple, but there is more to them than meets the eye, as Cook points out.
“Reducing the quantity of plastic required in the packaging process is never without its challenges. Perhaps the biggest of these is maintaining pack rigidity and ensuring the packaging is strong enough to hold the product without causing damage to either the pack or produce,” he says.
There is also the bigger question to consider: what actually constitutes environmentally friendly packaging? Is a tray made from rPET more or less sustainable than a paperboard-film combo?
To determine this, Swiss machinery manufacturer WM Thermoforming says it has to work on lifecycle inventory (LCI) and lifecycle assessment (LCA).
“We can use any thermoplastic material or substitute it with an alternative one, but only by studying LCI and LCA can we define if the packaging is more sustainable or not,” says area manager Gianni Morandi.
The need to consider the entire life cycle of a pack is a point that is taken up by Multivac’s Chrisp, who says: “Multivac has recyclable options for the majority of the packs produced on its equipment, but for materials to be classed as fully sustainable, more work must be done to find a solution for the collection and sorting of waste to ensure a circular economy.”
In the area of cup and pod thermoforming, where German company Gabler (represented in the UK by Engelmann & Buckham) is a specialist, the challenge is the same, but the solutions are different. Here, thinwalling and the emergence of compostable materials are the main sustainability strategies being pursued.
“We have done trials with new green materials (PLA) and found that the processing of these materials isn’t that different to other common materials. Due to this, there is no need to make any significant changes to our equipment. An important factor when processing PLA is machine stability, which is something that we can guarantee,” says Matthias Klein, area sales manager at Gabler.
When it comes to reducing material usage when producing plastic cups and pods, Klein says that thermoforming has the edge over injection moulding, due to the potential for thinwalling. Gabler has also developed stacking technology that enables its machines to handle very thin thermoformed products.
Thinwalling or ‘lightweighting’ initiatives have been underway in the drink bottle industry for many years and have reached the point where further progress is limited by the consumer’s ability to handle very light bottles rather than a blow moulding machine’s ability to produce them.
For example, Krones says its latest generation of Contiform blow moulding machines is capable of producing bottles at a weight lighter than most companies would be content releasing them into the market and at the fastest speeds available.
“The design of Krones’ Contiform blow moulder with its linear motor stretch rod system and multi-stage air recycling allows us to go lighter than a consumer could handle without crushing the container and spilling liquid,” explains Paul Chapple, technical manager at Krones UK.
This is why, instead of taking more weight out of containers, beverage bottle users and designers have turned their attention to cap design, where Chapple says a shorter/smaller neck finish helps to reduce the plastic content. Besides lighter weight containers, the use of rPET is now standard in the beverage market – the question is only one of how much, according to Chapple.
“Krones Contiform blow moulders can and already are blowing bottles using 100% recycled PET, so the question is one of material availability rather than technical constraint. PET will become increasingly available and important as our governments introduce deposit return schemes and the tools for a circular economy,” says Chapple.
He adds: “Other materials are in development, though currently none of them are at a stage of replacing PET. Krones is constantly testing and working with different materials so that we are ready when they appear.”
New technology round-up: Thermoforming/injection moulding
This month, WM Thermoforming Machines is hosting an open-house at its headquarters in Stabio, where it is showcasing its new steel-rule-knife machine, the FLEX 92, and the latest version of the TWIST 700. It says these two machines are able to run new materials that respond to current market trends, providing more and new environmental solution-oriented polymers such as different recycled and bio-degradable materials.
Husky Injection Molding Systems has launched its next generation HyPETTM HPP5e system, a refinement on its HPP platform. It says that significant technology improvements have resulted in a smarter, more intuitive system that delivers better energy savings, reliability, preform quality and user friendliness. At the heart of the platform is an intelligent, adaptive technology that uses feedback from pressure and actuator sensors to determine the optimum pressure required to effectively and efficiently mould every application.
Ulma Packaging’s newly launched TFS 200 MSV thermoformer provides three pack styles: MAP, skin and vacuum, on a single machine. The new machine is also compatible with both recyclable board and paper board. It is suitable for packing a range of frozen and fresh food products, including but not limited to meat, fish, cheese and deli meats.
Sumitomo (SHI) Demag has developed a new programme that synchronises ejector and mould speed, shortening the mould open time to optimise productivity, improving the quality of packaging, and reducing avoidable plastic waste. Designed for the company’s newest IntElect all-electric series, this latest advancement is said to ensure that components are clear of the mould before it closes again. As well as preventing falling packaging parts being crushed, it helps to mitigate damage to expensive lid and closure mould tools, says Sumitomo.
Shorter set-up and changeover times as well as film waste reduction of up to 75% are some of the benefits promised by GEA’s new PowerPak PLUS thermoformer, thanks to refinements to the film systems and sealing station. Both the top and bottom films are now motor-driven and synchronised with the machine’s advancing cycle, and the sealing station structure has been redesigned to accommodate this new film set-up and for easier access. PowerPak PLUS can also be operated in tandem with Oxycheck, the non-invasive inline quality control system for MAP.
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