The material, which helps components in vehicles, pipelines, and medical products to achieve top performance, makes a discreet arrival—as a simple granulate. In a functional factory hall with a concrete floor, a packing machine fills it into 25-kilo bags, which are stacked 40 to a pallet. A truck then transports them out of the Evonik Chemical Park in Marl to the customers.
But their content is something special: It’s polyamide 12, or simply PA12. It belongs to the premium class of plastics. It is needed where things get technically demanding—for example in the production of fuel lines and coolant pipes in cars. Such components have to deliver maximum performance in order to withstand chemicals, constant vibrations, and dirt. PA12 is processed into lightweight and robust tubes for the energy industry and is also used to make crystal-clear, scratch-resistant sunglasses in the eyewear sector.
Evonik has been the global market leader and a reliable supplier of this plastic for more than 60 years. “PA12 is mainly used in special applications, but demand is growing. As recently as 2021, we further expanded PA12 capacity here in Marl, making it the world’s largest production plant for this high-tech material,” says Florian Hermes, a sustainability expert in the High Performance Polymers business unit at Evonik.
One of the properties that are expected of a contemporary material today is sustainability. The European Union aims to achieve a climate-neutral Europe by 2050. Many of Evonik’s customers are facing the challenge of reducing their carbon dioxide emissions and making a contribution to greater sustainability within the supply chain—including in the plastics industry. Reducing the CO2 burden that the raw materials bring with them is a major lever for reducing greenhouse gas.
»We aim to meet all their needs. A universal solution under the motto 'One size fits all' is not possible here.«
FLORIAN HERMES Sustainability expert in the High Performance Polymers division at Evonik
"Making our PA12 even more sustainable is a key aspect of our strategy,” Hermes confirms. The challenge here is that because customers use the material in very different applications, they also have different requirements. “We aim to meet all their needs,” says Hermes. “A universal solution under the motto 'One size fits all' is not possible here.” So an entire product family has grown up around the core material. For companies, this means that they can choose between several PA12 variants with different levels of sustainability. This helps them to meet their own carbon reduction targets and legal requirements without having to make costly changes to their production processes. That’s because the plastic always remains the same—PA12, with all of its outstanding properties.
Sustainable in stages
The polyamide 12, which is individually tailored to each customer and each application, is produced in a large plant network in the heart of the Marl Chemical Park. In the uppermost section of the complex, the raw polymer is mixed with other additives. These include pigments, and sometimes also glass fibers that make the plastic particularly strong, or impact modifiers—additives that give the plastic certain mechanical properties.
The plastic mixture passes through a long pipe to the next part of the system—the heated extruder, where rotating metal elements knead the ingredients until a homogeneous mass is created. This is then pressed through dies into pencil-thick continuous strands. Finally, razor-sharp steel blades shred the cooled strands back into fine granules. The granules then go to the filling department and from there to the customers—automotive industry suppliers, eyewear manufacturers or shoe factories. It’s an apparently simple process that results in a genuine high-tech product.
How sustainable the respective polyamide 12 is in the end is determined at various points along the production chain. In principle, every variant of the PA12 granulate is produced using 100 percent electricity from renewable sources. Evonik purchases corresponding quantities of green electricity for this purpose. But customers can also choose additional sustainability options for an extra charge. For example, polyamide production requires a lot of steam and heat. These are usually generated from natural gas. As a green alternative, Evonik offers steam and heat from waste-based biogas.
Florian Hermes and his colleagues have also tackled the issue of petroleum. For example, customers can opt for polyamide 12 that is made entirely or partly from recycling materials—from end-of-life tires, used plastics or oil from agricultural waste.
These raw materials enter the production chain at the very beginning, where petrochemical base materials for polyamide production are also processed: in the refineries of the energy companies. The oil is broken down into its components—including a gaseous mixture of carbon chains with four carbon atoms each—in so-called crackers. This mixture is called crack C4. It’s the basic feedstock for the polyamide synthesis.
The crack C4 is transported via a pipeline or by ship to Marl, where it is further processed: first to butadiene, then to a chain of twelve carbon atoms, which gave PA12 its name. The polyamide is then produced via further steps. All of these steps take place on a large scale at a single location, making the Marl plant unique in Europe.
A guided cycle
If, instead of crude oil, the crackers in the refinery are fed with used cooking oil, for example, the carbon footprint improves. “When a customer opts for the variant based on such bio-circular raw materials, we ensure that appropriate quantities of used fats are purchased for the overall process and then processed in the refinery,” says Hermes. The quantity of sustainable materials used is reflected in what is called the mass balance. This determines the proportion of environmentally friendly raw materials contained in the end product.
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The concept behind it is comparable to that of green electricity from energy suppliers. If you want, you can buy electricity from solar and wind production, which is usually somewhat more expensive. Although in the end it is not possible to determine whether an electron that the customer draws from the socket at home was fed into the grid by a wind farm or a coal-fired power plant, the calculation balances overall. “That’s also how our mass balance works. You can no longer chemically distinguish whether a molecule in the finished product comes from petroleum or frying fat,” Hermes explains. For PA12, the raw materials that previously came from fossil sources can thus be completely replaced by recycled, bio-circular or bio-based raw materials.
“For the mass balance approach to work, transparency and trust are important,” says Hermes. “That’s why we have our procedures checked by independent auditors every year.” Evonik has received the ISCC Plus sustainability certification. This ensures that the product actually delivers the environmental effect it promises. Chemically, it is ultimately identical to PA12 made from petrochemical raw materials. The quality of the plastic therefore does not change due to sustainability.
Paving the way for customers
“Our aim is to reduce the carbon footprint of our product as much as possible—and through the various sustainability approaches to give customers the opportunity to choose between the sustainable variants,” says the expert. Evonik is thus a pioneer that supports buyers in achieving their own sustainability goals. After all, if a company offers products made from sustainable raw materials, this contributes to reducing its own carbon footprint and that of its customers.
Evonik sells the sustainable polyamide under different names: the standard version produced with green electricity as VESTAMID, and the version that uses steam and heat from biogas as VESTAMID RFP—the RFP stands for “reduced footprint.”
The third variant, which is particularly sustainable, brings everything together: green electricity, biogas, and sustainable raw materials, especially those made from plant waste. It is offered under the name VESTAMID eCO. VESTAMID eCO achieves a CO2 reduction of up to 70 percent compared to a polyamide made from petroleum and electricity generated using coal.
The RFP variant is currently particularly popular with customers from the 3D printing industry. However, instead of granules they use a fine polyamide powder named VESTOSINT®. This is sintered layer by layer in the 3D printer so that an object grows in height
Sustainability is a sales driver
The eCO variant has also already taken off in the market—especially among eyewear manufacturers. They require a crystal-clear, unbreakable, and scratch-resistant plastic. These properties are provided by the polyamide that Evonik offers to the optical industry under the name TROGAMID. “Many customers want sustainably produced eyeglasses,” says Jennifer Haßelberg, who heads the corresponding market segment.
As a pioneer in the optical industry, ZEISS Sunlens has already converted its entire polyamide portfolio for non-prescription sunglass lenses to this sustainable high-tech plastic. According to Haßelberg, fashionable sports or lifestyle eyewear are often luxury goods. “The slightly higher material costs can be offset by a slightly higher sales price. That works in this market, as all sides are calling for sustainability,” she says.
Demand is currently increasing, particularly in the Italian fashion market. Customers can have a clear conscience if they buy sustainable eyeglasses, and manufacturers can not only score points with their customers but also improve their own carbon footprint.
The high-performance material can be used to produce eyeglass lenses as well as frames. “End customers want lightweight and robust eyeglasses that can withstand sun creams and disinfectants—and are forgiving if you accidentally sit on them,” says Haßelberg. But this is just the beginning. “Especially in the high-priced fashion world, you also want to sell a unique feeling, and that’s exactly what we create with TROGAMID eCO: sustainable and flawless.” The customers are delighted that top-quality, crystal-clear plastic that does not have a yellow tinge or residues such as crumbs or stains can be produced from plant waste.
A new life for old plastic
And the ambition of Evonik’s researchers goes even further, because they also want to intensely focus on recycling the PA12. That is why they have launched another sustainable variant on the market—VESTAMID R, where the R stands for “recycling.” For VESTAMID R, Evonik collects polyamide residues, from customers’ production facilities among other things, in order to shred them and then add them to the polyamide ingredients in the compounding process. “This diversification of raw material sources is important in order to obtain material in sufficient quantities,” says Florian Hermes.
Hermes and his colleagues have also examined the recycling of products made from PA12 that have reached the end of their useful life. Together, they went to scrap dealers and waste recyclers to get an idea of what the polyamide 12 residues look like when they are removed from cars and trucks years later. On their tour, they also wanted to find out whether enough PA12 residues in total were being collected. One of the results: As a rule, brake pipes and fuel lines are so heavily soiled that it does not make sense to reprocess them for mechanical recycling.
In such cases, chemical recycling makes it possible to close the material cycle. Mixed plastics that are not used for mechanical recycling are heated until a dark brown liquid known as pyrolysis oil forms. In the future, it could be produced from so-called shredder light waste. This fraction makes up around a quarter of the final material when end-of-life vehicles are shredded as part of the vehicle recycling process.
The pyrolysis oil could be cracked again in a refinery to obtain crack C4 for PA12. The European Union is currently pushing ahead with a regulation in the form of the new End-of-Life Vehicles Regulation, which has as one of its aims an increase of the recovery rate in the automotive industry.
The draft provides for the use of more recycled plastic. “Such European and international regulations are increasing the demand for sustainable products among many manufacturers. Our PA12 made from pyrolysis oil will help with this,” says Hermes. “Our different PA12 variants give customers the opportunity to decide for each product how much sustainability they want and how much they are willing to pay.”
Lifecycle-Management
Evonik’s lifecycle management team has compiled all the findings and data on energy consumption, carbon dioxide emissions, and land and water use in a polyamide 12 life cycle assessment.
What was previously created manually within a few weeks could be automated for some types in the future. The assessment calculated which sustainability paths—from the oil to the finished product to recycling and the alternative raw materials—save the most CO2. The results of the life cycle analyses are openly available on the Internet. This provides maximum transparency—especially for customers. “They should be able to understand the sustainability of our PA12 in detail—not least for the sake of their own climate balance and a smaller carbon footprint,” says Hermes.
Transparency is fundamental when it comes to making the economy more sustainable and working together across company boundaries. “Ultimately, you can only make a difference jointly. The entire supply chain must work together, from the raw material supplier to the end customer.”
