Local Recycling instead of a Global Supply Chain

The Corona crisis has caught the global community largely unawares. That is hardly surprising, since we are in a completely unprecedented situation. But it makes it difficult to assess yet what effect the crisis will have on the plastics industry.

The Corona crisis has caught the global community largely unawares. That is hardly surprising, since we are in a completely unprecedented situation. But it makes it difficult to assess yet what effect the crisis will have on the plastics industry. Besides the development of the global economy, there are two other key issues that might be relevant.

The Corona crisis is focusing attention on the shelf life of foods again. Instead of every day, many customers now only shop once a week. Stockpiling of goods is also becoming more common again. Foods are being stored for longer and therefore have to stay edible for longer. The importance of a long shelf life for foods will stick in consumers’ minds even after the crisis. For manufacturers of plastics packaging, who have been in the firing line in recent times, that is good news, since it is precisely what their products accomplish.

The crisis has also shown how vulnerable global supply chains are. Shutdown of factories in one part of the world no longer only affects the local region, but leads to bottlenecks in other countries, too. There is nothing new about this recognition, but in the past it usually only affected individual materials and sectors; now it hits entire industries. In the future, therefore, regional supply relationships and production could become more important. This opens up opportunities for plastics recyclers, especially in regions where there is little local material production. After all, plastic wastes are already available locally and can be recycled back into raw materials. Sustainable management of plastics will therefore also improve supply security.

How these two issues can be combined is shown by various manufacturers of plastics packaging. They have developed products that ensure foods have a long shelf life, while also being easier to recycle. Our extensive Packaging Extra from page 8 presents some particularly interesting examples.

Editorial Streifinger

Streifinger, Florian

Approaches and Unresolved Problems in the Mechanical Recycling  of Flexible Multilayer Packaging

The challenges associated with recycling food packaging are particularly great in the flexible-packaging sector. Multilayer composites are often a hindrance to mechanical recycling, yet are irreplaceable in many applications. Replacements will not be found until recyclable and ecologically sustainable packaging solutions are devised.

Multilayer composites, which can consist of up to 12 layers, are mostly non-recyclable. This prevents material loops from being closed (Fig. 1), as the materials cannot be recycled to reusable secondary material for higher-value applications.

However, multilayer composites are an established packaging system, they now account for about 10 wt. % of the global packaging market [1] and they offer many advantages. The fact that different combinations of materials are possible affords a way to exploit their morphology and associated properties. Even thin layers are capable of acting as a barrier that will adequately protect the contents. Polarity, crystallinity, tacticity (the recurring sequence of side chains in the polymers), molecular weight distribution – each material has a characteristic constitution and thus has different application possibilities [2].

Closing the Material Loop through Mechanical Recycling

The entire value chain now has to do a rethink. The EU’s strategic goal of only putting recyclable or reusable packaging into circulation by 2030 is essentially unassailable. If the material loop is to be closed via mechanical recycling, new recycling solutions will have to be found and tested.

One solution under consideration is the use of mono-material instead of multi-material. This raises the question as to whether mono-material composites can serve as replacements for specialized multilayer composites. This is because any one material on its own is usually unable to act as a barrier against different environmental factors. Should a product, say, need to be protected against both water-vapor and oxygen, one limitation soon manifests itself in the morphology: non-polar polyolefins will protect against water-vapor, yet be permeated by oxygen [2]. So how can we continue to provide proper protection for products (such as crispy snacks which are vulnerable to oxidation) that have a wide range of requirements?

Mono-Material Approach Must be Developed Further

Mono-material solutions are every recycler’s dream, as they can usually be recycled without problems. Very thin coatings of metal oxides or of aluminum in thicknesses of 100 nm or less usually do not disrupt mechanical recycling. It has also been shown that EVOH polyolefin composites with an EVOH content of less than 5 % are easily recyclable. The plastic content of common combinations of plastics with sandwiched layers of aluminum (aluminum layer thicker than 5 µm) or paper is typically not mechanically recyclable. The same is true of composite beverage cartons, where usually only the paper content is recycled.

According to [3], theoretically recyclable combinations currently include composites comprising

<ul><li>Coatings of silicon oxide (SiOx) or aluminum oxide (Al2O3) for PP, PE and PET,</li><li>EVOH in a proportion of up to 5 wt. % for PP and PE,</li><li>PA in a proportion of up to 5 wt. % in PET, and</li><li>metallized foils, provided that they do not interfere with the sorting process.</li></ul>

In practice, economic reasons largely preclude these film grades from being either collected or mechanically recycled. What is more, there are many other packaging materials on the market that are still non-recyclable.

A trawl of online platforms reveals that some manufacturing companies already offer recyclable solutions for flexible food packaging and are substituting the recyclable composites mentioned above for previously used multilayer composites: mono-PE for muesli, mono-PP for fruit puree and muesli bars, metallized PP for nuts and seeds, vapor-deposited silicon oxide on PP for heatable convenience packaging. Also available are coated paper solutions which, if they are coated on one side only and they contain less than 5% plastic, can be licensed and recycled as paper.

However, recyclable barrier solutions currently have low market penetration (Fig. 2). In the case of individual food product classes, such as sausage and cheese slices or animal feed, the market is dominated by non-recyclable multilayer composites, because no other solutions exist that meet all the requirements of these product classes (Fig. 3). The issues here are machinability, sterilizability and even puncture resistance. Further developments are still necessary in this area.

Simply transitioning from non-recyclable multilayer composites to recyclable combinations will not close the loop (or more precisely: loops). This is because recycling of flexible packaging has been hindered up to now by a number of technical challenges, such as the diversity of polymers and combinations thereof, contaminants and residues, overlaps and assignability, and size allocations. Also standing in the way of recycling and reuse as secondary material are systemic problems relating to a lack of collection and recovery infrastructure, absence of economic viability, restrictive use permits, low sustainability, etc.

In some instances, systemic impediments are more complex than the technical ones. The bulk of scientific publications over the last ten years on the subject of recyclable flexible multilayer packaging report that one of the challenges is the fragmentation and lack of transparency of the value chain. This is made up of many players pursuing their own small-scale developments and projects and creating a huge patchwork of potential solutions. If larger reusable material flows are to be achieved, however, it is necessary for standardized approaches and (material) goals to be adopted as far as possible. Loops can still remain small, but they must be profitable from all aspects of sustainability (ecological, economic, social). It is becoming increasingly important to interlink all the elements in this value chain because there is no compelling case, from any aspect of sustainability, in favor of mechanically recycling flexible multilayer plastic films in their current composition.

A further problem arises in the case of ecological sustainability, for example. Although it may not be recyclable, nonetheless, highly specialized thin – and thus lightweight – flexible multilayer packaging is highly efficient, consumes very few resources and has a low carbon footprint. Replacing these materials with alternatives would nearly always entail higher resource consumption and greater environmental impact. With regard to plastic film recycling, the question also arises as to whether this is also ecologically justified if, say, the high effort entailed in collecting, sorting and recycling leads to a negative environmental footprint.

It is clear that our economy must move towards a circular model. However, this is not an end in itself, but rather should mitigate the negative environmental impact of our actions – as measured, e. g., in terms of resource consumption and carbon footprint. In this context, “recyclable” does not automatically equate with “more sustainable”.

1 Ellen MacArthur Foundation, The New Plastics Economy: Catalysing Action, 2017

2 Soroka, W.: Fundamentals of packaging technology, 4th Edition, Institute of Packaging Professionals, Illinois 2009

3 FH Campus Wien, Circular Packaging Design Guideline, 2019

Fig. 1. Gap in the circular economy: the pathway followed by resources is only 9 % circular on average worldwide. Just 91  % of the 92.8 billion t of minerals, fossil fuels, metals and biomass entering the economy each year is not recycled

Source: Altstoff Recycling Austria, EU, graphic:  © Hanser

Fig. 2. Redesign required: about 30 % of plastic packaging (measured by weight) cannot be mechanically recycled without a fundamental redesign

Source: Ellen MacArthur Foundation, graphic: © Hanser

Fig. 3. Stand-up pouch: typical composition of a non-mechanically recyclable pouch bag for wet feed

Source: Constantia Flexibles; graphic: © Hanser

Name - Hauptartikel

Anna-Sophia Bauer, MSc., is a member of the research staff in the Department of Packaging Technology and Sustainability at the University of Applied Sciences FH Campus Wien, Austria; <a href="mailto:anna-sophia.bauer@fh-campuswien.ac.at">anna-sophia.bauer@fh-campuswien.ac.at</a>

Dr. Manfred Tacker is the Head of Department of Packaging Technology and Sustainability at the University of Applied Sciences FH Campus Wien.

Verpackungsmaterial

Logistik

Blasfolienextrusion

Kunststoffverarbeitung: Maschinen und Komponenten

Flachfolien- und Plattenextrusion

Kunststoffverarbeitung: Verfahren

Extrusion

Kunststoff-Recycling

Kunststoffverarbeitung

Nachhaltigkeit

Umweltmanagement

Kunststoff-Verpackungsmaschine

Sondermaschinen

Designing Food and Consumer Packaging for Recyclability

The goal of the European Union (EU) to recycle all plastic packaging in Europe in an economically viable manner by 2030 is exerting enormous pressure on the packaging industry. It is very common that packaging films are made of different materials, and this causes challenges since they are often not easy to recycle. The demand is high for recyclable films which at the same time deliver the same or only slightly reduced food shelf life and packaging productivity. Various current examples show that this is possible.

The goal of the European Union (EU) to recycle all plastic packaging in Europe in an economically viable manner by 2030 is exerting enormous pressure on the packaging industry. It is very common that packaging films are made of different materials, and this causes challenges since they are often not easy to recycle.

The sustainability and thus the CO2 balance of plastic packaging must improve significantly. This can be achieved by multiple use of the involved materials. However, many currently popular packaging structures are not designed for recycling.

Packaging for consumer goods such as detergents, coffee and meat generally consists of several types of material such as linear low density polyethylene (LLDPE), LDPE (low density PE ), HDPE (high density PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), ethylene-vinyl alcohol copolymer (EVOH) and aluminium. These materials are combined in multiple layers to protect the product with minimal material usage while ensuring product quality. Usually, such multilayer and multi-material films are as thin as a human hair. The recycling of such packaging requires the separation of the different materials in order to achieve sufficient purity for recycling. This is technically possible in many cases, but very costly.

An alternative approach is to develop film structures with the highest possible proportion of just one polymer. If possible, an infrastructure to recycle such material should already exist. In Europe, for example, this is the case for PE. The aim is to develop film structures that apart from the polymer mainly used do not contain other materials which would interfere with the recyclability. Whether materials turn out to be critical in a particular material recycling stream, depends on how strongly they influence the recycling process and diminish the usability of the recyclates in further applications. Dow Europe, Horgen, Switzerland, together with various industrial partners, has developed mono-material PE-based packaging films, which continue to consist of multilayer structures but largely use one main material and, if necessary, materials compatible with the PE recycling stream.

The first example is dishwasher tabs packed in stand-up pouches. The packaging currently used in the market is mostly based on oriented, clear, printed polyester films, which are laminated to a coextruded PE film that serves to seal the pouch. The outer PET film with a high melting point fulfils, among others, the purpose of ensuring the stability and dimensions of the pouch during forming and sealing.

As an alternative, the concept of a mono-material film was developed that includes printing the film, which was co-extruded with a low-melting sealing medium and a PE with a higher melting point, and then coating it by extrusion to protect the printed image. This allows to combine high gloss of the overall film with the high melting point of the coated PE to improve packaging machine efficiency. A reclose mechanism (zipper) was also sealed into the package. Figure 1 shows the packaging implemented with the consumer goods manufacturer Reckitt Benckiser, Slough, Great Britain, and the packaging company Drukpol, Nowy Dwór Mazowiecki, Poland.

Machine-Direction Oriented PE Replaces PET

Other examples use machine-direction oriented PE (PE-MDO) as an alternative to oriented PET film, which is characterized by high stiffness, transparency and gloss. Windmöller & Hölscher, Lengerich, Germany, produced this printed PE-MDO film which was laminated with a co-extruded PE sealing film at Dow’s Pack Studios and formed into stand-up pouches suitable, for example, for liquid soaps at B&B, Hopsten, Germany (Fig. 2). In many applications, a good oxygen and water vapor barrier also plays a role in protecting sensitive food. As an alternative to metallized oriented PET and aluminum foils, PE-MDO films were also used in a collaboration of Dow, coating machine manufacturer Bobst, Prilly, Switzerland, Hosokawa Alpine AG, Augsburg, Germany, and the Italian company Elba, Magnago. The films served as carriers for very thin vapor-deposited barrier layers (Fig. 3). Biaxially oriented PE films are also being developed to serve as stiff, glossy, possibly metallized print carriers or as thin sealing films for packaging made of ideally only one material.

In addition, non-oriented, co-extruded films for use in mono-material bags have been developed in several projects. Reverse-printed stiff PE carrier films, for example, can be laminated with the above-mentioned sealing films that allow sealing at low temperatures. This concept was realized together with packaging manufacturer Transcontinetal, Montreal, Canada, and the company Mespack, Santa Perpètua de Mogoda, Spain (Title figure). The stand-up pouches produced could be equipped with PE zippers and sealed tightly. The use of individual, externally printed coextruded PE films containing an EVOH barrier layer was implemented in collaboration with packaging manufacturer Berry Global, Evansville, IN/USA, and food company Kellogg’s, Battle Creek, MI/USA (Fig. 4), and in another project with Georg Menshen GmbH & Co. KG, Finnentrop, Germany, and Plastiandino, San Rafael, Argentina (Fig. 5). In addition, this type of packaging can be protected with Dow’s Opulux protective finishing which protects the print image on mono-material pouches.

The examples given show that in many cases it is possible to switch from currently common multi-material packaging to mono-material packaging. The mono-material packaging concepts presented can be produced on most common packaging machine types such as vertical and horizontal form, fill and seal machines and horizontal stand-up and flat bag machines from the reel or as pre-made bags. However, adapted processing parameters must be selected.

In addition to the circular economy goal, the European Union has set the goal to substantially reduce food waste by 50 % by 2030. So far, this waste comprises about 20 % of the food produced in the EU. The shelf life of meat, for example, plays an important role in this context. Together with Kuhne Anlagenbau, Dow has helped to develop packaging that keeps meat fresh up to three times longer. Improved tough LLDPE and fast sealing plastomers are used for this purpose. At the same time, only one third to one tenth of the material is required compared to Modified Atmosphere Packaging (MAP). Such improvements can reduce food waste along the value chain. A good example are barrier shrink films for meat, which are coextruded as multilayer films with EVOH and oriented in several steps to produce very thin and tough films. These films ensure that the packaging and thus the meat is not spoiled during transportation.

The retail packaging for meat is also being continuously optimized. Vacuum skin packaging (VSP), for example, offers the possibility of enclosing the meat cleanly and keeping it fresh with very little film use. For this purpose, a carton is covered with a thin barrier film and the meat is positioned on it. Then another thin skin barrier film is pulled over the meat like a skin by means of vacuum. For the production of this type of barrier film, Dow offers various raw materials that are tailored to the functional requirements of this kind of packaging. The latest generation of VSP films has been produced with Windmöller & Hölscher on Aquarex lines and tested at Dow on Sealpac packaging machines. For the consumer, the packaging materials are easy to separate. She or he only needs to remove the small amount of film from the carton and place both materials separately in their recycling streams.

Recycling of meat packaging is largely not practiced today from a hygienic point of view. Nevertheless, the industry is working on technologies to recycle these multilayer barrier films, which are in principle recyclable. This includes the use of compatibilizer polymers already in the film and/or during recycling. With the compatibilizer embedded in the barrier film, the improved miscibility of the barrier polymers and the PE in the films leads to good recyclate properties in secondary applications. However, an important aspect in improving the recyclability of multilayer barrier films is that the shelf life of the food must not be impaired; especially when this leads to more food waste. It is therefore important to leave room for innovations in the currently being developed guidelines for recyclable packaging design, which will allow for a continuous improvement and increase in recycling rates. Plastics are too valuable not to reuse them.

Fig. 1. For these dishwasher tabs packages, a film coextruded with a sealing medium and a co-extruded PE film was printed and then coated by extrusion to protect the printed image. This kind of packaging replaces combined packaging made of PET and PE

Fig. 2. Machine-oriented PE can be an alternative to oriented PET films

Fig. 3. PE-MDO films serve as a carrier for very thin vapor-deposited barrier layers

Fig. 4. These stand-up pouches use externally printed co-extruded PE films. They have an EVOH barrier layer and use Retain compatibilizers for an improved recycling result of the packaging  

Fig. 5. The single material packaging is based on a single co-extruded barrier film with surface printing 

For these stand-up pouches, counter-printed stiff PE carrier films were laminated with sealing films with low temperature sealants 

Dow - Hauptartikel

Dr. Peter Sandkühler is a Principal Scientist at Dow Packaging & Specialty Plastics; <a href="mailto:psandkuehler@dow.com">psandkuehler@dow.com</a>

A PDF file of the article can be found at <a href="http://www.kunststoffe-international.com/2020">www.kunststoffe-international.com/2020</a>–5

Read the German version of the article in our magazine Kunststoffe or at <a href="http://www.kunststoffe.de">www.kunststoffe.de</a>

Kunststoffe

Photonik

Optik

Polyethylen

Kunststoff Werkstoffe

Thermoplaste

Standardkunststoffe

Verpackungstechnik

Polyethylenterephthalat

A Start-up Produces Organic Coffee Capsules Made of Wood and Plant Starch in Millions

Many people have good ideas and intentions. Few have the courage and determination to put them into practice. The young rezemo entrepreneurs Julian Reitze and Stefan Zender are one successful example. In 2019, some three years after their start-up was founded, the company was already producing well over one million compostable coffee capsules per year. A number that is growing rapidly. For the capsules, a compound of wood and plant fiber is processed on injection molding machines.

Many people have good ideas and intentions. Few have the courage and determination to put them into practice. The young rezemo entrepreneurs Julian Reitze and Stefan Zender are one successful example. In 2019, some three years after their start-up was founded, the company was already producing well over one million compostable coffee capsules per year.

The rezemo GmbH success story began with a coffee maker in a shared flat in Stuttgart, Germany. Julian Reitze and Stefan Zender were studying industrial engineering and management in Stuttgart, and during stays abroad had taken a dislike to carelessly disposed of consumer packaging. Coffee capsules made of aluminum or plastic, of which around 60 billion are produced worldwide every year, and the resulting mountains of waste were a particular irritation.

“We wanted to produce 100 percent compostable coffee capsules made from renewable raw materials and offer an ecological alternative to Nespresso products. By using waste wood as a basis, we are able to create an additional value-added stage,” Stefan Zender, who is currently responsible for marketing and sales as Managing Director, explains the basic idea.

Julian Reitze, who is responsible for technology and finances in the same position at rezemo, adds: “During our studies, we had access to an Allrounder injection molding machine at the Institute of Industrial Manufacturing and Management (IFF) and at the Fraunhofer Institute for Manufacturing Engineering and Automation (IPA). That’s where we taught ourselves the process of injection molding. With the intuitive Selogica control system and the help of a thick operating manual, it was basically easy.”

In order to transform wood into a granulate suitable for injection molding, it is embedded in a matrix of polylactide (PLA) made from plant starch. The material is thus based entirely on renewable raw materials. The entrepreneurs tried out different compounds and optimized the process, as the granulate needs to melt homogeneously, without burning the wood content. In the beginning, the students made frequent use of the machine manufacturer hotline and have also visited Arburg GmbH + Co KG headquarters in Lossburg, Germany, several times.

Since then, they have continuously improved the capsules and the injection molding process. rezemo now cooperates with a mold maker and injection molding company near Lake Constance, which also uses Allrounders injection molding machines. The aim is to increase the percentage of wood fibers and to further reduce the layer thickness of currently 0.4 mm at the thinnest point. Another objective is to avoid sprues as far as possible by using hot runner molds, thereby also reducing material consumption.

Rezemo places emphasis on regional proximity, not only when it comes to injection molding technology. The company, which currently employs eight people, purchases its coffee from a roasting plant in its home region. The base material for the 3,5 g weighing capsules, foodgrade wood shavings from sawmills, comes from domestic forests. Since this is scrap in wood processing and the shavings for further processing at rezemo do not have to be chemically treated, the process chain is resource-friendly and the product is suitable for use with food.

The coffee capsules are sold in an online shop and through regional coffee houses. Retailers and hotels are also showing increased interest. “There is enormous demand. Many hotels have Nespresso machines in their rooms and there is a great deal of awareness for sustainable products,” says Stefan Zender.

The young entrepreneurs are currently exploring the international market. “For 2020, we are planning for a production volume in the double-digit million range. In addition, we aim to position ourselves more strongly as packaging experts. This is because other disposable products such as cosmetics jars or containers for cleaning products could also be produced from our material, making them carbon neutral and 100 percent biodegradable,” says Julian Reitze.

Sawdust and wood shavings from the woodworking industry, PLA as a binding agent – the recipe for ecologically compatible coffee capsules

Julian Reitze (left) and Stefan Zender have made their idea for 100 percent ecological coffee capsules a reality

... Julian Reitze, one of the two founders of rezemo GmbH

Will the capsules survive the conditions in the coffee machine – we are talking about up to 19 bar pressure and up to 100 °C water temperature – unchanged?

The capsules naturally withstand the brewing conditions during the brewing process. This is also important – a critical water pressure must build up in and around the capsule, which then leads to the sealing paper bursting. The extraction and above all the crema depend decisively on this.

Is the process of filling coffee different from conventional capsules made of aluminum or plastic and how do they seal the wooden capsules?

The wooden capsules can be processed on standard filling machines. The process is the same. The sealing medium must be matched to the capsule. We use a coated cellulose to ensure both the appropriate barrier effect and a stable connection via the sealing seam.

What do gourmets say to the wooden capsule – how long does the aroma last?

Our coffee capsules, which we sell e. g. via our web shop, have a best before date of nine months. . With the general trend towards fresh and preferably regional foods, we believe this is becoming more and more accepted by the market. To be honest, there is no need for a shelf life of 24 months for coffee.

Is there a kind of organic certification for compostability?

Our capsule consists of wood shavings and a small amount of PLA. This bioplastic is obtained from renewable raw materials and is tested and certified for compostability. The wood fibers come from sustainable PEFC certified forestry and are naturally compostable as a direct natural material. Our capsule is the first on the market that – certified by DIN CERTCO – is 100 % bio-based, i. e. made from renewable raw materials.

Under what conditions and in what time do the capsules degrade?

The duration of decomposition generally depends on the environmental conditions. These include in particular the ambient temperature in the compost, the season, the place of installation, ventilation, humidity and the microbacterial environment. In industrial plants, e. g. for organic waste, these are relatively constant. Therefore a rough decomposition time can be given there. The throughput in such plants is about two to six weeks. Since home composting often has very different environmental conditions, the composting time can only be estimated. Comparable to a branch of softwood or a pine cone, one should rather expect six to twelve months here.

Interview: Dr. Clemens Doriat, Editor

Dr. Bettina Keck is working in the Corporate Communications at Arburg GmbH + Co KG, Lossburg, Germany.

Spritzgießen

Verbundwerkstoffe / Werkstoffverbunde

Biokunststoffe

Holz

Faserverbundwerkstoffe

Andere Werkstoffe

PC-Based Control in an In-Mold Labeling System Helps Decorate Plastic Lids

In-mold labeling is the ideal solution for today’s customer requirements in the packaging industry. Companies need high-quality, durable machines with maximum availability that can produce a wide range of packaging designs with flexibility and economic cycle times. To implement such systems efficiently, Swiss specialty machine manufacturer Beck Automation implements PC-based control and drive technology from Beckhoff as its standard automation platform.

The spectrum of customer requirements for in-mold labeling (IML) ranges from cost-effective basic systems through to customer-specific special machines. Beck Automation AG in Oberengstringen, Switzerland, is one of the pioneers in the field of IML systems with more than 30 years of experience. As a current example of the solution competence of the family-run company, which was founded in 1934, Nino Zehnder, Head of Sales and a member of the executive management team, cites a six-way IML system for decorating plastic lids: “This machine is for plastic containers used in the food industry. The most common items being made with it are lids to cover 1-liter containers for products such as yogurt, but the same machine can also decorate the body of the container.”

With in-mold labeling, a previously printed label that has the same base color as the final product (for example, the lid of a yogurt container) is placed in an injection mold. When the plastic is injected, cools down and hardens, it combines with the label to form the finished product. This process is more flexible than affixing printed labels, says Nino Zehnder: “IML is especially suitable for packaging design in the age of Industry 4.0 and lot sizes of 1 because you don’t need to modify a printing machine for every change, which is expensive and time-consuming.” The Beck Automation system can produce up to 5000 plastic lids per hour, each with its own design or even an individual QR-code if necessary.

For precision and durability, the IML system is mounted on a solid welded steel frame. The system attaches laterally to an injection molding machine so that its servo-controlled shuttle arm can reach into the mold. When the shuttle arm moves into the open injection mold, it picks up six finished lids on one side while simultaneously inserting six new labels for the next injection molding process.

During this process, the IML machine inspects the lids with a vision system for quality assurance before stacking them. During the stacking process, the machine also separates the next six labels in order to place them on the main shuttle arm for the next insertion pass into the injection mold (Fig. 1).

Nino Zehnder points out the performance capabilities of the IML machine: “The entire cycle with six plastic lids takes only about four seconds. The machine also features exceptional flexibility. It can be adjusted for other lid sizes, shapes or quantities very quickly and easily. Another advantage is the automatic magazine changeover, which makes it possible to refill the labels without interrupting the process.”

Advantages of PC-Based  Control Technology

As Christoph Jenni, Head of Software Development, explains, Beck Automation first decided to use PC-based control technology in 2011: “Even back then, PC-based control technology impressed us with several basic advantages such as the ease with which you can implement remote access for effective customer support. Another outstanding feature of PC-based control from Beckhoff was the ability to make system changes online, i. e. reloading modified program parts while the control program is running. Compared to the previous PLC-based solution, we also benefited from the powerful axis control with extensive diagnostic capabilities as well as from the fast and easy-to-use EtherCAT communication standard, which replaced the traditional individual wiring.” Nino Zehnder also points out the benefits of a Windows-based software system: “Its openness ensures maximum flexibility. For example, we can easily export data as an Excel file or use Windows’ many capabilities for a user-friendly operator interface.”

According to Nino Zehnder, the worldwide availability of Beckhoff technology (Fig. 2) and support is also important for a globally active company like Beck Automation: “Since our systems are extremely durable, we must also make sure that the components are available for the long term. Even after ten years or more, spare parts and newer, yet fully compatible products are still readily available.”

Another factor is the exceptional modularity and scalability of PC-based control, adds Christoph Jenni: “Depending on the machine’s size and features, the control technology can be optimally adjusted without requiring much additional engineering. For example, we can easily adapt the number of servo axes to the respective requirements. And unlike other systems, PC-based control offers an unlimited number of I/O channels, which leaves all options open.”

Servo Drive Technology Increases Machine Flexibility

Beck Automation also employs servo drive technology throughout its new six-way IML system. Its easy configuration results in significant benefits, particularly during setup changeovers. The machine features four AM8000 series servomotors, which are controlled by TwinCAT 3 NC PTP software (Fig. 3) via two single-channel AX5103 and AX5118 Servo Drives or a two-channel AX5203. The AM8063 servomotor with 29 Nm of standstill torque makes for a highly dynamic main axis (Fig. 4).

There are also two AM8032 (2.37 Nm) and one AM8033 (3.22 Nm) equipped with holding brake, which are used to implement, among other things, the shuttle motion in order to guide the plastic lids along the inspection system with a sufficiently short cycle time, says Nino Zehnder. In addition, the servo drive technology is much less jerky than pneumatics, which increases the machine’s durability due to the reduced inertia forces.

The other servo axes are used to take the labels from the magazine and to stack the finished lids. Another positive feature is the One Cable Technology (OCT) from Beckhoff, says Christoph Jenni: “OCT reduces the wiring and assembly effort significantly. And the electronic type plate makes it much easier to commission, troubleshoot and possibly replace devices.”

A CX5130 Embedded PC (Fig. 5) with an Intel Atom processor running at a clock speed of 1.75 GHz provides sufficient performance for all control and motion sequences. The broad spectrum of the Beckhoff Industrial PC portfolio is another critical advantage, says Jenni: “Depending on the requirements or the size of the machine, you can easily deploy more powerful IPCs or multi-core processor technology without having to change the control software. This makes us highly flexibly as far as the system design is concerned.”

The same applies to the TwinCAT software: “The existing motion control library has met all our requirements so far. We could even implement special features like data exchange via OPC UA very easily with the help of a corresponding TwinCAT function.” And the integrated TwinSafe solution has delivered additional efficiencies, because the EL6900 TwinSafe Logic terminal and the optional AX5801 TwinSafe cards for the drives made it possible to significantly reduce the wiring and the space requirements for the safety doors and the emergency stop function.

With IML systems from Beck Automation, a broad range of plastic containers and lids can be labeled efficiently and flexibly

Fig. 5. The CX5130 Embedded PC and the I/O level with EtherCAT and TwinSafe terminals are extremely compact

Fig. 1. In each processing step, the IML system takes six labels at a time from a magazine and places them into the open mold of the injection molding machine

Fig. 3. Together with the AM8000 OCT servomotors, the AX5000 Servo Drives provide an efficient and dynamic motion control solution 

Fig. 4. Two of the machine’s four AM8000 servomotors move the main arm (motor on the right, top) and the shuttle (motor on the left, top)

Fig. 2. Nino Zehnder, Head of Sales and a member of executive management, and Christoph Jenni, Head of Software Development, both of Beck Automation, and Robert Urech, Area Sales Manager of Beckhoff Switzerland (left to right), in front of the new six-way IML system

Beckhoff Automation GmbH & Co. KG offers specially adapted solutions for the plastics industry, such as the six-way IML system for container lid decoration described here.

<ul><li> PC-based control and drive technology provides the basis for highly flexible machine design</li><li>CX5130 Embedded PC as a powerful control device</li><li>TwinCAT 3 NC PTP, AX5000 and AM8000 for precise and dynamic motion control</li><li>OCT for minimized installation, troubleshooting and maintenance requirements</li><li>Efficient, system-integrated TwinSafe safety technology</li></ul>

<ul><li>Compact and flexible system design</li><li>Long machine design lifecycle</li><li>Output up to 5000 plastic lids per hour</li><li>Quick product changeovers down to lot size 1</li></ul>

<a href="http://www.beckhoff.com/packaging">www.beckhoff.com/packaging</a>

Dipl.-Ing. Thomas Kosthorst works in the Business Management Plastic Processing Machines/Hydraulic Applications at Beckhoff Automation GmbH & Co. KG, Verl, Germany.

Steuerungen (Hardware und Software)

Automatisierungstechnik

Folientechnik (IMD, IML, FIM, u.a.)

Servomotoren

Antriebe

Elektromotoren

Computer Hardware

More Resource-Efficient Materials for Thermoforming

Contrary to the current perception, plastics, as a component of packaging materials, often represent the most environmentally sound option. The plastics industry is currently undergoing a transformation, shifting the focus onto the realization of closed material loops as well as reducing the resource input with highly efficient materials.

Thanks to suitably designed packaging, foods can be efficiently protected without significantly increasing the ecological footprint of a product [1]. Flexible plastic packaging is superior to other materials, such as glass and cardboard, in many ways. While 1 kg of plastic can be used to package some 56  kg of a product, cardboard can only package a half, and glass only 1/30 of this amount [2]. In the last 20 years, in Germany alone, changes in consumer behavior have meant that the amount of packaged consumer goods transported in a heavy goods vehicle has increased by about half, while transport distances have also risen [3]. This makes an additional saving of packaging weight a significant instrument for conserving resources.

An important and very versatile representative of plastics in the field of packaging materials is polypropylene (PP), which accounts for a high proportion of approx. 19 % of the European plastics market [4]. If only the flexible packaging sector is considered, this figure even rises to 30 % [5]. This is mainly the result of the material’s properties, such as its very good chemical resistance, low water-vapor permeability and higher mechanical strength compared to polyethylene [6]. The disadvantage is the narrow processing window [7] that is typical of semicrystalline polymers, so that amorphous polymers, such as polystyrene are often preferred, especially for thermoforming.

The aim of a joint research project between the Institut für Kunststofftechnik (IKT), University of Stuttgart, Germany, and Constab Polyolefin Additives GmbH, Rüthen, Germany, is to improve the property profile of polypropylene for the production of thermoformable semifinished film products by using fully miscible blend components. First, the thermal energy requirement for processing is to be reduced, and the processing temperature window enlarged. Second, the mechanical performance of the product is to be improved, so that the wall thickness of the packaging and therefore the necessary material consumption is reduced. It should be possible to process the developed blends by conventional extrusion as a drop-in solution.

Manufacturing Thermoformable Semifinished Film Products

To further highlight the positive properties of PP, the project partner Constab first manufactured masterbatches on a pilot scale. These comprised blend materials based on PP in each case, as well as a blend component that is fully miscible with the base material. From the blends that resulted, a screening was carried out jointly between the project partners IKT and Constab to define a large range of different film formulations. Table 1 shows a selection of formulations that have proved particularly useful.

The formulations were extruded into 300  mm-wide films with thicknesses 1 mm, 0.8 mm and 0.7 mm. The masterbatches were fed together with the basic material via the main hopper of the extruder (PP homopolymer: MFI 3 @230  °C/2.16 kg, laboratory extruder with a screw diameter of 30 mm and an L/D ratio of 25; manufacturer: Collin Lab & Pilot Solutions GmbH, Maitenbeth, Germany). The temperature profile at the extruder was chosen constant for all trials; the temperatures at the cylinder and die varied between 190 °C and 230 °C. The slit die with a width of 300 mm has a coathanger die, which is also controlled to a die temperature of 230 °C via four separate heating zones. The output melt film is then brought to the desired thickness with a calendering unit (type 136/350, manufacturer: Collin) and cooled until it was dimensionally stable. The roller unit (Fig. 1) consists of a chill roll (144 mm diameter), a cooling roll (72 mm), as well as a smoothing roll (72 mm). During processing, the most important machine parameters, such as motor current, die pressure and throughput, were logged and used to determine the specific energy consumption for processing the different film formulations.

After the film extrusion, the thermal properties were investigated by means of dynamic differential scanning calorimetry (DDSC) with a DSC 2 (manufacturer: Mettler Toledo, Greifensee, Switzerland). For the purpose, 4 mm-diameter circular chips were punched out of the films and automatically tested in aluminum crucibles. At the start of the measurement cycle, the test chamber was first cooled down to -80 °C and kept at this temperature for 5 min., then heated to 240 °C at 10 K/min., and cooled down to -80 °C again at -10 K/min. after two minutes isothermal phase, before the second heating process began. The second heating cycle was used to evaluate the changes in the thermal characteristics of the materials, for example the melt enthalpy and thus the necessary energy for melting.

The films were subsequently formed into cups in a comprehensive thermoforming study [8]. This was done using a laboratory thermoformer (type: LDFG32b; manufacturer: Illig Maschinenbau GmbH & Co. KG, Heilbronn, Germany). For performing the tests, a temperature-controlled negative cup mold was used. As can be seen from the flow chart of the thermoforming process (Fig. 2), the tensioning frame, together with the film, first moves between the radiant heaters, which heat the film to the forming temperature range. The subsequent forming was achieved with compressed air and vacuum, together with mechanical prestretching. The plug is driven by a servomotor, which prestretches the material into the mold cavity at a rate of 500 mm/s and a travel of 73 mm. The remainder of the forming is then reached shortly after the start of prestretching by the combination of compressed air and vacuum. After a holding phase, the thermoforming process is terminated by the opening of the mold. The basic parameters are shown in Table 2.

By varying the heating time, pressure and plug position, the aim was to find the optimum parameters for each film formulation, which were then used to manufacture at least five cups. For this, a cup was manufactured using a basic setting, and the result of the thermoforming was assessed. In the first quality analysis, poor forming definition, blow holes, poor surface quality, or uneven wall-thickness distribution led to rejection and changing of the setting parameters. With the collected empirical values, the best process settings for each material could then be found iteratively, by adjusting first the heating time and then the plug travel. The wall thickness distribution of the thermoformed cups was determined with a thickness gauge (Panametrics Magna Mike 8500; manufacturer: Olympus, Mainz, Germany).

To assess the part quality, the compression resistance according to DIN 55440–1 was determined on the manufactured cups with a universal tensile, compression and flexural testing machine (type: Zwick 1474; manufacturer: Zwick/Roell, Ulm, Germany). The test specimen, positioned between two pressure plates, is loaded axially by the raising of the lower pressure plate (advance rate 10 mm/min. ± 3 mm/min., initial load until measurement start 1 N). The forces occurring and the travel distance are recorded by a force-path sensor, until the test is terminated by a maximum compression path of 50 mm or a sudden drop of >20 % in resistance force. Five cups made from each film formulation were tested under standard climatic conditions.

Analysis of the Efficiency Potentials by Modification

The project uses an integrated analysis to demonstrate how the masterbatches influence the materials’ resource efficiency. This article presents the efficiency potentials with one example in each case: the energy saving reached during processing as well as the material saving potential due to improvement of the product properties of a cup.

The measurement of the melt enthalpies of the reference material and modified formulations (Fig. 3) shows that the modifications in most cases mean that a reduction of the melt enthalpy can be expected. The reduction of the melt enthalpy here is a measure of the thermal and mechanical energy to be supplied during the extrusion process and was at most 15.8 %. In addition, the extrusion required lower die pressures and thus a reduction of about 10 to 20 % in the mechanical energy input. From rheological studies, this can be traced back to improved flowability of the blends, which is also an advantage for the thermoforming process, since the films manufactured can already be processed at lower temperature, which further saves up to 20 % of the heating time and enlarges the processing temperature window.

The material saving potential is elucidated by investigating the compression resistance of the manufactured cups (Fig. 4). For this, the maximum compression force of the 1 mm-thick reference film (53.6  N) is compared with the 0.7 mm-thick thermoformed films of the new formulations, with which maximum forces of up to 66.5  N to could be attained. This corresponds to an increase of the compression force of 24  % with simultaneous reduction of the wall thickness of 30  %. The increased compression resistance of the cups can be attributed to the increase of the material stiffness; at the same time, the addition of the masterbatches optimizes the thermoformability of the PP, so that a more uniform wall thickness distribution results.

The results of the thermoforming trials show that suitable modification of polypropylene allows a material saving of over 30 %. This is achieved through improved thermoformability of the blend, manifested as a more uniform wall thickness distribution. Likewise, through the addition of the masterbatches from the project partner Constab, a reduction of the melt enthalpy was achieved, allowing an energy saving of up to 15 % in the film extrusion process. The developed materials are clearly superior to conventional polypropylene as regards conservation of resources.

Within the remaining project time, it is now to be tested how selected formulations can be processed when scaled up to an industrial thermoforming process on a production scale. Furthermore, it will be examined to what extent the positive results can be transferred to biobased plastics such as polylactides (PLA).

[1] Bonten, C.: Kunststofftechnik – Einführung und Grundlagen. 2. Aufl. Carl Hanser Verlag, München 2016

[3] Statistisches Bundesamt Wiesbaden, Verkehr auf einen Blick, 2013

[4] Plastics Europe Market Research Group, Plastics – the Facts 2019, 2019

[5] AMI Consulting, High Barrier Flexible films for Food Packaging, 2016