The regeneration and reuse of felts in manufacturing processes, including the paper industry, fall within the framework of the circular economy. The adoption of design criteria oriented toward material recovery and the use of chemical recycling of polyamide make it possible to transform this waste into new resources, reducing the use of virgin raw materials and the carbon footprint. This opens up new perspectives for paper mills in terms of more sustainable material management
Raw materials are precious in every production cycle, especially when dealing with high-value material. Optimizing their use and, above all, using them sustainably is a way to do business — particularly in an era in which attention to circularity has become an unavoidable necessity. In the paper sector, a high-value raw material is represented by press felts. To date, the end-of-ife management of these felts represents a genuine environmental challenge for the paper industry, and it is for this reason that Voith has developed highly interesting solutions.
New potential
According to data presented by Voith, every year in Europe thousands of tons of felts reach their end of life and are primarily sent for incineration. Globally, the quantity increases considerably. The result is a significant loss of high-value raw materials, and from this awareness the group’s circularity strategy — presented by Anne Klaschka, Global Product Manager Press Felts at Voith, at Miac 2025 — takes shape.
“We have calculated that around 3,700 tons of felt per year go to incineration or landfill. And this is only in Europe”, Klaschka specifies, noting that at a global level the value is about four times higher, approaching 15,000 tons per year. This considerable quantity of material still has enormous potential, and Voith’s experts have decided to work precisely on this aspect. “Our goal is to give companies the possibility to use this material by bringing it back into the loop to give it new life and thus create new felts”.
The starting point is therefore the transformation of a complex industrial waste into a resource through a methodology involving design, collection, recycling, and new production.
To understand the possibilities offered by recycling, it is necessary to start from the structure of press felts themselves. From a materials perspective, felts consist of polyamides (PA) in percentages ranging from 85% to 100%. The base fabric may include PA6, PA6.6, PA6.10 or PA6.12 yarns, while the batt layer is generally composed of PA6, PA6.6, and PA6.10 fibers. There are also other materials such as copolyamides or polyurethane. Even in cases where the composition is 100% polyamide, it is often a mixture of different types, with PA6 content in conventional felts typically below 75%. This complexity makes mechanical recycling ineffective and explains why, until now, incineration or landfill has been the main destination for these products at the end of their useful life.
Starting from design
This is where Voith’s decision originates to intervene upstream, rethinking the product from the design stage. “When you want to use a new product, you must start from the beginning, from the way the material was conceived”, Klaschka continues. The concept of “design for recycling” therefore becomes the fulcrum of the strategy. The declared goal is to achieve a closed material cycle, reducing the use of virgin raw materials and maintaining high quality in the final product. This has led Voith to redefine the composition of felts, prioritizing polyamide 6 (PA6) in the yarns of the base fabric, with a content between 75% and 100%, and maximizing the percentage of PA6 batt fibers to over 90%.
The choice of PA6 is not accidental. Among the various polyamides used in industry, PA 6 is particularly suitable for chemical recycling, thanks to the possibility of being brought back to its original building block, caprolactam. “We discovered that PA6 is the best material for recycling”, the manager explains, “and we developed a collaboration with a specialized company, the Italian Aquafil S.p.A.”.
The group, headquartered in Arco in the province of Trento, has long been a pioneer in chemical recycling of polyamide and represents a key partner for Voith in creating a fully circular material flow.
Regenerated fibers
The technological core of the entire project is the advanced chemical recycling used by Aquafil in the production of its high-quality PA6. The flagship of its production is called Econyl — a regenerated PA6 of high quality, made entirely from various types of postconsumer PA6.
In the standard production of PA6 polymer, the starting point is the organic monomer that forms its basic structural unit: caprolactam. This compound is obtained from crude oil and, to form PA6, undergoes polymerization. This process requires high energy consumption and results in a significant product carbon footprint (PCF). At the end of their lifecycle, however, PA6 products contain not only the polymer but also additives, pigments, and contaminants accumulated during use.
In the Econyl process, by contrast, polyamide-6 waste is subjected to depolymerization — this is the essential difference — namely the chemical recycling process capable of breaking polymers down into their original building blocks. Specifically, the polymer chains of polyamide 6 are returned to the caprolactam building block. During this stage, all impurities are separated and removed, producing an extremely pure raw material, often indistinguishable from virgin material. “Through depolymerization, the compounds can be cleaned and brought back to caprolactam to obtain polymer again”, Klaschka explains, emphasizing how the resulting material is ideal for being reintroduced into the production chain as a high-quality secondary raw material.
In addition, compared to traditional production, this process allows an energy-consumption reduction of about 65%, eliminating the initial stages linked to extraction and synthesis from fossil sources.
The regenerated caprolactam is then transformed into Econyl, which has 100% recycled content and is characterized by a quality that makes it suitable for the production of technical yarns.
True circularity
In parallel with product redesign, Voith has also launched a structured program for collecting used felts. Currently, Klaschka reports, two collection centers are in operation in Germany. “Customers organize the pickup and transport of used felts with Voith’s support to the collection centers. The post consumer goods are than bailed and transported to Aquafil. The recycling process is managed by the industrial partner Aquafil”.
This is a far from trivial logistical step, she notes, considering the volume of the products involved. “These felts are very heavy, not easy to handle”, Klaschka admits, explaining how building an efficient collection network is one of the next steps for extending the model globally.
Once the products have been processed, Voith can close the loop by reintroducing the recycled material directly into its own production processes. One example is Voith internal monofilament production plant, which today manufactures around 160 tons per year of yarns made entirely from Econyl. The plant also uses exclusively green electricity and sends its internal production waste back to Aquafil, further contributing to system circularity.
The result is a yarn with a carbon footprint that, the manager recalls, is about 80% lower than a standard yarn.
Felt production
A further step concerns the actual production of press felts. “At our plant, it was possible to integrate into our Infinity +Green felts a share of about 16% yarns made entirely from Econyl”, Klaschka continues. In the initial phase, therefore, all machine-direction yarns were replaced with regenerated yarns. Again, production waste is collected and sent for recycling, contributing to a further reduction of the overall environmental impact.
From an environmental-performance perspective, “using our Infinity +Green felts allows a reduction of the product’s carbon footprint between 15% and 20%. If the used felts are also sent to Voith’s recycling program, the total PCF reduction can reach up to 31% compared to a standard felt destined for incineration”.
Thus, by giving paper mills the option to replace their felts with Infinity +Green, Voith enables them to save approximately 16% of carbon footprint immediately, Klaschka notes. “In combination with sending the felt for recycling, the share of carbon-footprint reduction increases to 31%, and this is, definitely, a great result”.
Certified circularity
This circular approach therefore also allows paper producers to directly benefit from sustainability choices — not only in terms of reduced emissions and waste, but also through traceable results. Voith, Klaschka recalls, issues its customers a certificate attesting to the CO2-emission reduction associated with the new felts and with the recycling of felts at end of life, reinforcing transparency along the entire value chain.
The circularity of press felts is therefore not the result of a single intervention, but of an integrated strategy that begins with design and involves industrial partners, logistics, recycling technologies, and internal production processes. “If you want to recycle and be sustainable, “design for recycling” is fundamental — start from the beginning, not from the end”, Klaschka reiterates. With the support of an experienced partner like Aquafil and with the progressive expansion of collection networks, Voith intends to make this model increasingly widespread. “We move forward together toward sustainability”, the manager concludes, summarizing a vision in which product quality, industrial performance, and circular economy must be seen more and more as parts of a single path.
Infinity +Green was awarded the “German Sustainability Award 2026” in the Products category, which serves as significant recognition of Voith’s commitment to sustainable innovation and its forward-thinking approach.