Clack, clack. Alexander Azzawi opens the black plastic case. Inside are two plastic bars glued together, connected by a silver metal strip and fixed between two clamps. Next to them is a key. “Just turn it,” says Azzawi, as he often does at trade fairs. A light comes on immediately and something in the suitcase starts to work. “We use the metal foil to heat the adhesive,” says Azzawi. “Then the two plastic parts can be easily separated from each other.”
While the humming quietly continues inside the demonstration case, Azzawi, Head of Lifecycle Solutions at Creavis, explains why it works.
His team has developed a special binder for polyurethane-based adhesives that replaces conventional binders. During bonding, the other components of the adhesive react with the innovative binder and form a three-dimensional network.
However, the bonds are designed so that they break at temperatures above 100 degrees, and the adhesive no longer sticks. That’s exactly what’s happening now. Azzawi pulls the two plastic bars apart without any problems. “It’s a bit like cutting a thread in a knitted sweater in some places so that the fabric falls apart,” he says.
Debonding on demand
The principle is called “debonding on demand”. Glued joints are released from each other exactly when necessary. Thanks to this technology, products are easier to dismantle or repair, and it’s easier to recycle the individual components. That’s how debonding on demand helps to close recycling loops. This works for smartphones and laptops as well as other everyday items such as shoes. For example, if the sole and the upper can be separated more easily, the components can be recycled according to material type.
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But manufacturers of electric cars are also interested in bonding the body and the battery together rather than screwing them together in future. This saves weight and simplifies the design. Evonik is currently engaged in various discussions, for example in a development partnership with the adhesives specialist Delo, about where and how debonding on demand can already be used today.
The time is ripe for alternatives to the classic “make and throw away” approach. This is especially true for plastics. Currently, more than 400 million tons of plastic are produced every year, and demand is expected to almost double by 2050. One reason for this is that the superior product properties of high-performance polymers in many applications make lightweight construction possible and thus enable electric cars to drive further, for example, while the mechanical properties of fiber-reinforced plastics stabilize the rotor blades of wind turbines and ensure that more green electricity is generated.
The greater the increase in demand, the more urgent it is to retain these valuable materials in the material cycle at the end of their service life. This is because the global plastics industry’s operations are still largely linear. On the one hand, more than 90 percent of plastics are today produced from petroleum, and on the other, a substantial proportion of plastic worldwide ends up in landfill, in combined heat and power plants or even in the environment. An alternative is needed. The circular economy closes material cycles, turns waste into raw materials and thus helps to conserve resources and protect the climate.
Rethinking recycling
In mechanical plastic recycling, plastic waste is sorted after collection. Only unmixed waste can be recycled without any major loss of quality. This already works well for beverage bottles made of polyethylene terephthalate (PET), for example. However, this route is blocked for mixed or heavily contaminated wastes. They cannot be reused and are therefore directly landfilled or incinerated.
Circularity must therefore be rethought: not from the end, but from the beginning. The goal is to design products from the outset in such a way that they can be kept in circulation or recycled for equivalent applications and in the highest possible quality. That’s how to get started in the resource-conserving circular economy.
“To establish cycles, we need ‘design for recycling’ and mechanical and chemical recycling methods,” says Patrick Glöckner. He heads Evonik’s Next Markets Program, which focuses on circular packaging and plastics recycling. “Ultimately, it’s about conserving fossil resources and minimizing the incineration of residues,” he says.
Legal requirements support this process, so that circularity has become an important part of the industry. Evonik bundled its activities for the plastics cycle in the Global Circular Plastics Program as early as 2020 and expanded the focus to other material flows a little later with the Circular Economy Program. The idea is to design products and processes in such a way that less and less fossil raw materials are required and they meet recyclability requirements.
»For this to succeed, you need the right design from the outset—design for circularity«
Patrick Glöckner Head of Evonik’s Next Markets Program
In addition, increased efficiency and better-quality recyclates make recycling more economical for Evonik’s business partners. The aim is to create plastics that can be recycled in an ecologically and economically sensible way, “And for this to succeed,” says Glöckner, “you need the right design from the outset—design for circularity.”
Evonik builds networks
Anyone who takes circularity seriously must consider all parts of the cycle. This means asking questions of all the companies in a value chain: What quality requirements apply to a particular material? How do the material flows work? Which processes are used? To explore these issues, Evonik is also increasingly approaching brand manufacturers and other stakeholders, such as recycling companies, with its Next Markets Program. “Everyone has very different priorities, and often one isn’t aware of the challenges facing the others,” says Glöckner. Evonik intends to change this by establishing networks and opening up markets that tie in with existing businesses.
Thanks to its long-standing, established business relationships, Evonik has insights into the needs and capabilities of many companies along entire value chains. This holistic view enables the company’s experts to provide them with advice and support—as well as the right additives to decisively advance the circular economy in many areas. The result is a system solution that makes plastic packaging materials easier to recycle.
How do you get the ink off the packaging?
Every network begins with the first links. When it comes to printed plastic, this is where hubergroup comes in. hubergroup is an internationally active printing ink manufacturer that produces 172,000 tons of ink annually at seven locations. Its products are sold to print shops—for example to those that provide packaging with logos, content information and best-before dates. To ensure that plastic films, bottles or cups can be used several times, the printed ink must be completely removed. Deinking—removing printing ink—is the keyword.
The challenge is that the components of the ink are tightly bound to the polymer structure of the plastic, and can interfere with the recycling process and reduce the quality of the recyclates. There is still no solution that washes off nitrocellulose-based printing inks on an industrial scale in an economically viable way. Methods involving solvents, high energy consumption or other disadvantages do exist, but there is no simple approach.
“We wanted to change that,” says Christian Schirrmacher, Head of Research & Development for Printing Ink Additives in EMEA at Evonik Coating Additives. “We’ve analyzed the entire value chain, and we see that we need to start directly with the ink manufacturers. Thanks to our solution, they can incorporate the deinking functionality directly into the ink without having to adapt further production steps, so the hurdles are minimal.”
TEGO Res 1100 is the name of the co-binder from Evonik, produced at the Darmstadt site. It is already added to the ink during its formulation. It’s a polymer that reacts to changes in the pH. It works as soon as the mechanical recycling of the shredded packaging begins, in a kind of giant washing machine. If sodium hydroxide (NaOH) is added as a base, the pH of the lye changes. This pH shift activates TEGO Res, weakening the bonding between the components of the ink and the plastic so that the ink is removed. “Our tests show that TEGO Res delivers excellent deinking results—quickly and even at temperatures as low as 40 degrees.”
Effortlessly integrable
Once TEGO Res had passed the laboratory tests, Schirrmacher called hubergroup: “We’ve got something, would you like to try it out?” Hubergroup wanted to. The company not only confirmed the laboratory results but also tested them on an industrial scale. And the co-binder really can be easily integrated into standard formulations of solvent-based inks. The inks are just as easy to work with, and retain their performance. Processes and machinery do not have to be changed.
But the most important thing is that deinking during subsequent recycling is so efficient that the recyclates are of a higher quality than in conventional processes. “Everything worked. The Evonik product is an interesting option, both technologically and economically,” says hubergroup manager Lars Hancke.
Industry’s interest in integrated recycling solutions is growing, especially in the European Union. Take packaging, for example: From 2026, a new packaging regulation will apply to all EU member states. In terms of recycling, it places comprehensive requirements on packaging in the European market. This makes a deinking solution that is already applied with the ink a selling point. Consequently, Evonik Laboratory Manager Christian Schirrmacher speaks of a unique product with huge market opportunities far beyond Europe.
Recycling in the automotive industry
Paint removal plays an analogous role in the automotive industry. In a consortium project with BMW and other partners that is funded by the German Federal Ministry for Economic Affairs and Energy, Evonik has investigated the question of how painted bumpers can be reused. “The parts are made of polypropylene and are not actually made to be recycled,” says Michael Hagemann, Head of Marketing for the plastics additives business of Interface & Performance at Evonik. “After all, the paint on the bumpers should still adhere firmly to the surface even after years of road use.”
Two steps need to be completed for recycling. The first is to remove the paint from the old bumpers. The second challenge is that the polypropylene that is separated from the paint and then recycled must be of such high quality that it can be used to produce new bumpers that meet the highest standards in terms of both performance and safety. And the new paintwork must remain attractive for many years.
To meet the first challenge, Evonik has developed a water-based and environmentally friendly process in which the old bumpers are shredded and stripped of paint. Only very few residual particles of paint remain. This is crucial in order to produce a high-quality recyclate.
The polypropylene granules are injection molded into new bumpers and then painted. This second challenge was also mastered in the project with BMW: “The paint looks just as good and is just as durable as the paint on new bumpers without recycled content,” says Michael Hagemann. In the Next Markets Program, the experts are working on commercializing the solution, which can also be used for recycling other painted plastics.
This is good news for the automotive industry and its suppliers. It too has a responsibility to use more recyclates. The corresponding regulation could even come into force this year. It requires cars to be built in future in such a way that parts can be removed and replaced more easily and that a minimum proportion of recycled plastics is used in production.
The trend toward monomaterials
The European Union is by no means alone in its efforts to promote recycling and the transition to a circular economy. Legal requirements to reduce CO2 emissions and conserve resources exist worldwide (see box). Both targets can be achieved by recycling more plastic and then reusing it, for example.
This is sometimes a problem. “Some food packaging, for example, looks like it’s made from one material and is therefore recyclable, but in reality it consists of five, seven or even nine ultra-thin layers of different plastics—and with the best will in the world it’s impossible to separate them,” says Evonik manager Hagemann. “One solution is to work with monomaterials wherever possible.” Hagemann aims to ensure that unmixed plastics can be mechanically recycled particularly well.
This places high demands on the packaging design. Packaging made of pure PET, for example, has rarely been used until now, partly because the individual pieces of the packaging are difficult to join together. Evonik has therefore developed heat-sealing coatings that can do just that. Instead of the multi-layer composite systems commonly used today, monomaterial packaging for food can thus be used more frequently.
This places high demands on the packaging design. Packaging made of pure PET, for example, has rarely been used until now, partly because the individual pieces of the packaging are difficult to join together. Evonik has therefore developed heat-sealing coatings that can do just that. Instead of the multi-layer composite systems commonly used today, monomaterial packaging for food can thus be used more frequently.
Chemical recycling complements mechanical recycling
If monomaterial can not be used, the chemical structures must be broken up. This makes it possible to recycle more complex plastics. The usual food packaging made of polyolefins can be liquefied. The resulting pyrolysis oil can then be fed back into the cycle. Chemical recycling can even be advantageous for monomaterials—such as polyurethane foam mattresses, which cannot be mechanically recycled as they cannot be melted.
An example of how this process works can be seen in a mattress from the British manufacturer The Vita Group, which is made from up to 100 percent recycled polyol. The footprint of this mattress is 70 percent lower than that of standard mattresses. This feat is made possible by a new hydrolysis technology from Evonik that enables polyurethane to be split and polyols to be recovered in the process.
This is accomplished using a catalytic system to break the chemical bonds quickly and efficiently. Polyol and toluene diamine (TDA) can be recovered in this way. The latter can be converted to the isocyanate toluene diisocyanate (TDI) in a subsequent reaction. TDI and polyol are exactly the substances required for the production of polyurethane.
“Our process enables a major step toward a closed material cycle in the polyurethane industry. Thanks to the high-quality recovered material, significantly less fossil raw materials are needed to produce new mattresses,” says Emily Schweissinger, Technology Manager at Evonik Comfort & Insulation.
Given that 40 million mattresses are produced every year in the European Union alone, the Vita Advanced Mattress is a real step forward. “Just five years ago, this technology was considered impossible,” says Natalie Watson, Group Director of Sustainability at The Vita Group, in the trade press. “Today we have proven that foams can be produced with a high recycled content, significantly reduced emissions and without compromising on durability. Innovations like these only come about when suppliers, partners, and internal teams work together with a common goal.”
The process is currently being tested in a pilot plant in Hanau; the prospects for scaling up to the next size are good. An independent panel of experts has recommended that the state of North Rhine-Westphalia use the European Union’s Just Transition Fund to support the construction of a demonstration plant at the Marl Chemical Park. As soon as official approval has been granted, the technical planning can begin.
Recycling needs cycles
Deinking with printing ink manufacturers such as hubergroup, chemical recycling for mattress producers such as The Vita Group, debonding on demand with the adhesives specialist Delo—Evonik is in talks with players at various stages of the value chain, in order to achieve success together. “To close the cycle, we need cooperation with all partners,” says Evonik manager Glöckner. This type of collaboration is the foundation of a functioning circular economy, he adds. “Only if everyone understands what drives the various partners can we work together to develop the best solution for each case.”
This enables plastics to be kept in circulation over a long period of time. “And for this to succeed,” says Glöckner, “you need the right design from the start.”
