TECHNOLOGY | PET
New additive for use in reactive compounding
modularity to achieve a smaller footprint. BoReTech integrated multiple equipment processes represent- ing two or three functions into a single unit. The new PET bottle recycling system also
incorporates the company’s sixth-generation ES process technology that offers cost-effective production of premium quality rPET flakes. Fea- tures of the ES Process include highly automated equipment, an efficient in-line water circulation and water-saving system and low-energy consumption that achieves stable production, reduces labour requirements, and improves product quality. The new unit, which the company says has received FDA approval, produces rPET flakes with low impurities that are oriented for food-grade PET bottle production. The company says one of the big advantages of
Above: KUZ has used BYK’s Scona TPPET 4214 PA additive in reactive compounding of rPET
Additives company BYK has been working on enhancement of rPET material that cannot be used in bottle production. Examples of PCR PET collected in Germany’s Dual System scheme include clear packaging films, thermoformed trays, presentation packaging and blister box inserts. Flakes reprocessed from this stream may contain small quantities of contaminants and when combined with factors such as thermo-mechanical and hydrolytic decomposition reactions, this rPET cannot be reintroduced into bottle production processes. BYK has developed an additive for use in reactive compounding to enhance the properties of this material which makes it suitable for injection moulding compounds. The company’s Scona products are mostly non-polar polymers that are modified with additional func- tional monomers via chemical grafting. Its Scona TPPET 4214 PA additive is a polymer modifier based on PET functionalised with GMA. “Due to its reactive epoxide groups, the additive works as a viscosity enhancer in polycondensation polymers,” says BYK in a white paper. “The higher molecular weight also increases viscosity during incorporation into the base polymer. In this way, excellent processability is achieved during extrusion, thermoforming, and even foam injection moulding.” Scona TPPET 4214 PA has been developed by BYK to have a significantly higher molecular weight. Its use in reactive compound- ing of the non-bottle rPET stream results in a significant increase in melt viscosity throughout the compounding line, says the company. This was verified in work carried out at Kunststoff-Zentrum (KUZ) in Leipzig, Germany using a ZE25Ax47D-UTXi-UG co-rotating twin screw extruder from KraussMaffei. The Intrinsic Viscosity of the rPET flakes was increased from 0.64 dl/g to 0.79 dl/g. (To read the BYK white paper, written by Jörg Garlinsky and Andre Rapthel from BYK, and Annerose Hüttl from KUZ, click here.)
24 PLASTICS RECYCLING WORLD | November/December 2023
the ES process is the intensive hot washing module. It can configure the number of hot washing devices according to needs, and through an optimised design it increases the friction force and improves the washing effect so the rPET flakes can be washed cleaner. The design of this intensive washing module is compact and simplified, and so occupies less floor space. BoReTech also made performance enhance- ments in other functional equipment for its PET recycling systems with innovative designs. It developed a heat-shrinkage label scrapping machine for its PET bottle recycling line that removes labels from bottle bales and uncom- pressed bottles that have a volume of 250-2,500 ml. The input capacity can reach 4,000 kg/hr and the label separation rate is over 95%, the company says.
Improved washing The new design of its Hydro Washer improves the rinsing efficiency of traditional vertical rinsing equipment and requires a footprint of only 3 m2
.
The unit adopts a high-speed cleaning mode and internal special design structure to effectively remove impurities and additives that reside on the surface of plastic flakes. It also designed what it calls a Multi-Channel
Zig-Zag separator used to collect PET fines and suspended small impurities from the PET bottle recycling production line. It is separated through multiple channels by negative pressure to improve the separation rate. In the field of quality control, BoReTech also developed a polymer purity tester to detect and determine the cleanliness of recycled PET flakes according to the throughput of the PET melt. The unit can collect the current, pressure, temperature, rotation speed, weighing measurement and other
www.plasticsrecyclingworld.com
IMAGE: KUZ
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