Solid state polymerisation of PET

摘要

The present invention is a process of making strap using both post consumer and non-post consumer PET of wide distribution intrinsic viscosity (IV) through direct solid state polymerization in a non-peletized state to produce PET with an increased, heterogenous IV suitable for high performance strap extrusion. The process increases the IV of post-consumer resins, consisting principally of polyethylene terephthalate (PET), by preferably chopping the post-consumer plastic into flakes and chunks, rolling the flakes and chunks, preheating the flakes, and further heating the pre-heated flakes and chunks in an atmosphere of hot nitrogen gas, thereby increasing their intrinsic viscosity. PET polymers having increased viscosities provide a polymer useful in manufacturing a high performance strap material.