Interview with Klaus Schäfer and Matthias Sch...
Interview with Klaus Schäfer and Matthias Schmitz, BB Engineering

Do spinning and recycling go together?

Matthias Schmitz, Head of Engineering Recycling Technology (l.), Dr Klaus Schäfer, Managing Director (r.) (Source: BB Engineering GmbH)
Matthias Schmitz, Head of Engineering Recycling Technology (l.), Dr Klaus Schäfer, Managing Director (r.) (Source: BB Engineering GmbH)

BB Engineering has been concentrating on recycling system development work. In this interview we discussed how the seemingly different business units interact and how the recycling business profits from the existing extrusion and spinning systems know-how.

BB Engineering has its origins in the manufacture of extrusion and filtration systems for synthetic fiber spinning equipment. How did it come to open a new business unit dedicated to PET recycling?
Dr. Klaus Schäfer: Our original business was, and remains, focused on components such as extruders and filters for processing the most diverse polymers into synthetic fibers, but also into films and on developing and distributing other products. Soon, our portfolio was complemented by our own compact spinning system – in the form of the VarioFil. Our extruders and filters have also been used for rPET for many years now. We first supplied components for rPET back in 2005. For these reasons, PET recycling was not something completely new to us. In 2012, we unveiled the VarioFil type ‘R’, which also spins rPET granulate into high-end yarn. Then, in 2016, we went a step further with the type ‘R+’: the direct processing of bottle flakes using our compact spinning system – in other words, recycling and spinning in a single step. The background to this was to dispense with the intermediate step of producing the granulate, hence saving lots of energy and cutting conversion costs, and to create high-quality POY from bottle flakes.

What potential benefits do you see in the recycling of synthetic fibers?
KS: Apart from the social responsibility of acting in a resource and environmentally friendly manner, we believe that recycling fibers presents our customers with considerable commercial opportunities. Firstly, there is production waste. Despite spinning technology becoming ever better, there is always waste in the form of B-quality goods, caused by over-production and during start-up and retooling. Instead of simply disposing of this – in view of constantly rising prices for raw materials and decreasing availability – nevertheless valuable material, it is far more economical to process it and return it to the production process. Yarn manufacturers can not only cut costs, they also become more autonomous. Furthermore, general developments, such as increasing population densities and fast fashion, are creating ever greater demand for polyester and polyester fibers. Here, many major textiles manufacturers have set themselves ambitious targets with regards to the utilization of recycled fibers. So, you can now see that the potential benefits of fiber recycling are tremendous.

Processing virgin material into films and filaments, and recycling polyester are actually 2 completely different processes. Where do you acquire your know-how?
KS:  Of course, these are 2 completely different processes, but we view the necessary conversion into recycled material from perspective of the end product. The desired properties of the end product determine the requisite quality of the starting material and hence also the requirements for the recycled materials and their production. We come full circle. Hence, we know precisely what is important when recycling PET to ensure that further processors are able to use it to create high-quality products.

In theory, that sounds very promising. What does the performance look like in practice?
Matthias Schmitz: Our trials have shown that – in the right configuration – our high-end extrusion and, above all, our filtration technologies are able to produce high-end rPET granulate for high-quality POY (partially oriented yarn) or FDY (fully drawn yarn). Our system creates an intrinsic-viscosity build-up of up to 0.15 dl/g and homogeneity fluctuations of just ± 0.01 dl/g. We have achieved good results in our tests. In part, the recycled materials from our VacuFil systems even offer superior spinning properties compared to the virgin material used in the tests – particularly with regards to spinning breaks and lint formation. We offer our test system to customers and other interested parties for specific material and process tests.

Normally you have to accept compromises when using recycled materials. How have you achieved this? What is so special about the VacuFil process?
MS: Fundamentally, we use liquid-state polycondensation, which cleans more effectively than solid-state polycondensation processes. But the truly special feature with the VacuFil is, above all, our Visco+ component. With this, we have developed a unique vacuum filter system for viscosity build-up and viscosity homogenization. We currently have a patent pending here. Add to this the interaction with high-end extrusion, large-area filtration and the excellent degasification technology.
The interview was conducted by Mechthild Maas, Editor of TextileTechnology, with Dr. Klaus Schäfer, Managing Director, and Matthias Schmitz, Head of Engineering Recycling Technology at BB Engineering GmbH, Remscheid/Germany.

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