PETpla.net Insider 10 / 2016

MATERIAL / RECYCLING 14 PET planet Insider Vol. 17 No. 10/16 www.petpla.net Dust content and IV uniformity The MTR Technology provides low dust content of the product, even with- out installation of a de-dusting device, because of the use of an under- water cutting system and because of con- siderably fewer solid transport and handling steps. Furthermore in the MTR Technology the IV of dust parti- cles and the IV of the PET pellets is identical, because there is very little IV-increase in the chip-conditioning system. AA content resin and AA content preform Comparing the AA content of MTR technology resin with SSP resin typi- cally shows lower AA content for SSP chips. The reason is obviously the dif- ferent focus of the final process step of the two technologies:  MTR technology: Chips Condition- ing => focus on AA removal  SSP technology: SSP reactor => focus on IV increase  With long residence time at a tem- perature of approximately 220°C in the SSP reactor, the AA content will automatically drop to very low values. UIF has run numerous trials at industrial scale preform machines, which all showed a significant lower AA content in preforms from MTR technology resin: MTR SSP IV resin [dl/g] 0.83 0.80 AA resin [ppm] 0.75 0.6 AA preform [ppm] 1.7-1.9 2.9-3.2 Table 1: Comparison of AA in preforms, Husky Hypet 300 72 cavities, 21.3g pre- forms, 285°C The reason for the lower AA con- tent in preforms from MTR resin is the lower specific energy input during preform making, which has its expla- nation in the lower degree of crystal- lisation and the overall lower thermal stress of the MTR production process. Summary The latest development of “new style” SSP technology has definitely reduced the energy consumption compared to previous SSP technol- ogy. In one way it can be said that the SSP technology has finally followed the path that UIF has started with the use of the latent heat crystallisation in the MTR technology in the year 2007. But MTR is claimed to be still ahead of the competing technologies for the production of bottle grade PET resin with respect to total project cost, energy consumption, plant flexibility, fixed cost, raw material utilisation and maintenance cost. Additionally MTR technology is said to offer a variety of benefits for downstream users of PET resin, which include lower energy of fusion due to lower degree of crys- tallisation, low dust content and no difference in IV between normal size pellets and small size pellets or dust. MTR is intended to be one of the most economical ways to produce bottle grade PET resin fulfilling high product quality standards. www.uhde-inventa-fischer.com Fig. 6 Degree of resin crystallinity of MTR and SSP technology Fig. 4 Comparison of dust content and IV uniformity Fig. 5 Comparison of AA content of resin and AA-re-generation in preforms