PETpla.net Insider 07+08 / 2012

MATERIAL / RECYCLING 34 PET planet insider Vol. 13 No. 07+08/12 www.petpla.net 3.6t/h bottle-to-bottle recycling 100% purified Pure bottle to bottle PET purification represents the peak of PET recycling activities. Because the material comes into contact with foodstuffs it is required to pass a series of official as well as internal tests. FDA is only one of a number of such tests. And it is here where Starlinger, with its PET recycling equipment, is most at home. The company’s latest development is a 3.6t/h system, the recoStar PET 330, with the first systems going to England to Continuum Recycling and to Australia to Visy Food Plastics. In the meantime the third system is under construction at the Weissenbach plant. To allow for the high throughput rates, the system works with two single screw extruders, each 165mm in diameter, which are constructed in parallel on one base frame. The advantage of this 2twosingle screw extruder concept is compact design and no technical risk as the 165mm extruder is Starlinger’s best seller and well proven at various PET bottle-to- bottle recycling companies throughout the world. The two-stage preliminary drying of the flakes and the vacuum treatment of the granulate which follows extrusion, both of which are standard at Starlinger, are designed to take account of the high capacity. After the washing and the shred- ding comes the drying in two stages. In the first stage, hot air is applied to the flakes for about one hour to reduce the surface moisture. In the second stage, dry air is used for hygroscopic drying of the material in order to achieve a residual humid- ity of less than 50ppm. Many of the hazardous substances that need to be removed are already present in the exhaust air and are removed in the condenser. The exhaust air filters and condensers on the large system are so designed that they can be replaced during production. In the subsequent plasticisation process by means of the two extrud- ers, the screws are vented and there is again the possibility that hazardous substances may escape. Following granulation, the required IV is set up in the vacuum vessel with continu- ous throughput over the length of the dwell period. Due to the defined grain size of the granulate, and the unique design of the first-in first-out SSP reactor the post-condensation process is uniform and reproducible. As this takes place at the end of the process, the IV value set is maintained and can no longer be changed by means of any subsequent operation. In addi- tion, the AA content is very low as it is no longer able to build up by means of subsequent plasticisation and the associated thermal load. Despite all the possibilities inherent in the equip- ment, the input material is crucial to the quality of the recycled material. The better it is sorted and, (in particu- lar), washed the better it is. The purified material is suitable for foodstuffs.Overall, Starlinger has an annual installed capacity of around 300kt for top-notch PET bottle to bottle recycling worldwide and addi- tional capacity on PET bottle to sheet. Starlinger also supplies machinery for non-food application such as strap- ping and fibre/filament. Starlinger was founded in 1835 which means it has more than 175 years’ experience in building machines. The company’s roots are in textile packaging. It was Starlinger who engineered the circular loom for bags. As people had previously only been familiar with the flat loom, it used to be necessary to sew up the sides of the bags. Now the endlessly woven tube only needs to be sewn up at the top and bottom. Small bags are used mainly in Asia, S. America and the Middle East. There the infrastructure is not so well developed as in the industrialised countries and foodstuffs in bags fit very flexibly into the individual trans- port systems. At the heart of the 3.6t/h recoStar PET 330 system are the two compact extruders that are mounted closely together on one common base frame. The technical centre is open for customer trials throughout the year for both PET and non-PET applications such as PE, PP, PA, PS and others.