WEB EXCLUSIVE: Aspira One, a new amorphous PET from Eastman Chemical Co., Kingsport, Tenn., reportedly provides an optimal balance of recyclability, product performance, processability, and aesthetics compared to existing PET resins used in extrusion blow molded handleware and large bottles. “With resin identification code 1, Aspira One has the additional attribute of being compatible with the PET recycle stream,” says global market development manager Ron Salati.
Other PET resins for extrusion blow molding (EPET) are sold as crystalline pellets with high IV around 1.0, raised by solid-stating treatment to provide the necessary melt strength. This can result in gels, difficulties in using regrind, and the need for higher drying and processing temperatures. In contrast, Aspira One is sold as amorphous pellets with a normal bottle-grade IV of 0.7 and a normal range of drying and processing temperatures. With Aspira One, both trimmed flash and virgin pellets are amorphous , making it easier to add regrind back into the process, Salati explains. In contrast, current EPET resins typically require the amorphous flash to first be crystallized before it can be reused with crystalline pellets. This extra step requires additional equipment and energy consumption.
Additional benefits in processing include less polymer degradation (IV loss) from lower process temperatures, more homogeneous melt (no gels or unmelts), and no melt fracture—all of which lead to excellent clarity when run on wheels, reciprocating-screw and shuttle machines, according to Salati. Toughness of finished bottles is also said to be better than with EPET.