Melt Filters for the Recycling of Styrene-based Plastics

The core of the system used at Sysplast is a Leistritz extruder that was commissioned in 2021. The feed material is single-type regrind from the recycling of old electrical appliances and the processing of mixed post-industrial and post-consumer plastics. The majority of these plastics come from Energenta Recycling Solutions, which, like Sysplast, belongs to the Energenta group of companies. Sysplast currently has 14 employees, 11 in production, and produces approximately 40 t of recompounds per day, 70% of which are ABS, 20% PS and 10% PC/ABS; quantities that, according to managing director Ude Dobberke, are far short of covering demand.

Even carefully selected input still contains some impurities in the form of metals, other plastics, silicones, paper, etc. Processing into sophisticated recompound qualities therefore requires filtration of the melt in order to reliably separate even the smallest contaminating particles. Dobberke: “The electronics industry, including telecommunications, consumer electronics and the automotive industry, only accepts products whose processing and performance characteristics are on a par with new products.” What is required of an optimal filter, therefore, is a high throughput with high filtration performance and reliable, continuous availability over long running times: “Screen blockages and filter changes bring fluctuations in production that we cannot afford. And because we produce recompounds for premium applications, the filter must reliably separate impurities with minimal melt loss.”

Given these demanding requirements, Sysplast opted for an Ettlinger self-cleaning ERF 350 high-performance filter. Dobberke confirms that screen replacements are rarely necessary with this model: “We typically run our system continuously in three shifts over five days a week with constant output.”

Surface-coated plastics at a glance

Among the pioneering projects commenced by Sysplast is the recycling of electroplated plastics, mostly ABS, from the automotive industry and the sanitary and household goods sector. Together with the Freiburg-based Fraunhofer Institute for Process Engineering and Packaging (IVV), the company has developed a process in which both the plastic and the metals are completely recycled. Here, too, an Ettlinger ERF 350 has been removing residual particles from the metallisation process reliably from the melt since the end of 2021.

Sysplast is currently launching a second pioneering project together with the Chair of Plastics Technology at the University of Erlangen involving the recycling of painted, spray-coated and laminated car bumpers. The first tests have been completed successfully.

Fivefold increase in throughput by 2030

For the future, Dobberke plans to expand its existing activities and ramp up its development projects to an industrial scale: “By the end of the decade, we want to achieve a fivefold increase in our current output of around 10,000 tonnes per year and thus bring Sysplast into the top group of recyclers in this material group in the German-speaking region. A second new system will increase capacity by 17,000 t/a by the end of 2022. The upgrade of a decommissioned system will contribute an additional 1,500 t/a. Here too, Ettlinger melt filters will once again form part of the system.”