Technological watch

Single-piston backflush filter from Starlinger for use of recycled polypropylene in tape productionDestination circular economy: Starlinger's new backflush filter allows manufacturers of woven bags made of polypropylene tapes to use a proportion of recycled polypropylene of 50% and more in the tape extrusion process.

In times where buzzwords like sustainable packaging and closed packaging cycles are on everyone's lips, Starlinger & Co. GmbH is now able to provide another solution to the plastic packaging industry that will ensure greater sustainability. "With our SPB filter, we are offering tried and tested technology that enables woven bag manufacturers to use recycled material for bag production without compromising on quality and cost-effectiveness. As such, you get exactly the same specifications and properties with recycled input material as with tapes made from 100% virgin material," explains Hermann Adrigan, Head of Sales at Starlinger.

Especially when it comes to packaging made of tape fabric, which is characterised by its high strength properties, high-quality tapes are the most important requirement. The tear-resistant sacks are filled with up to 50 kg of contents - in the case of big bags, the fabric even has to sustain two to three tonnes of weight. When using recycled material, the Starlinger SPB filter ensures excellent melt filtration for the high tape quality required. "This enables fabric bag manufacturers to work even more sustainably and at the same time meet a criterion that is becoming increasingly important in the packaging market: the amount of recycled content in the product," says Adrigan.

50% and more of recycled contentIn tape production, impurities and, in many cases, the range of different polymers in the recycled input material cause problems such as filter blockages or tape tears, which, in turn, reduce production efficiency. The SPB melt filter from Starlinger, on the other hand, achieves a high melt throughput with excellent cleaning capacity even in the case of more heavily contaminated input material. This way, a stable production process and high degree of efficiency are ensured.

Thanks to the hydraulic backflushing function of the filter, the respective filter screen is backflushed and thus cleaned when a defined degree of contamination is reached. The backflush cycles are relatively short due to the high pressure build-up in the filter, and the extrusion process is not interrupted - an important criterion that saves material and time. Depending on the degree of contamination of the melt, the filter can achieve throughput rates of up to 720 kg/hour and allows for 50% and more of recyclate in tape production.

Know-how for a closed packaging cycle"For optimum recyclate quality, our division Starlinger recycling technology offers recycling plants that are tailored to the specific needs of bag manufacturers," adds Hermann Adrigan. "In principle, we at Starlinger combine the know-how and technology for "circular packaging" under one roof: From the manufacturing process and the packaging recycling process to reusing the recyclate for the same product. And our customers benefit from this. With our equipment, it is a lot easier for packaging manufacturers to use recycled material in the extrusion process because they can rely on the quality of the recycled pellets."

Design for Recycling is another important criterion for implementing a circular economy in the packaging sector. "In this respect, woven bags made of polypropylene are the perfect example," says Adrigan. "They are a mono-material packaging consisting of 99% PP - even if they are coated. Considering this, it is obvious that the bags should be collected after usage and recycled. We want to promote and advance this process with our technologies."