Poly(alkylene terephthalates) are among the fastest growing plastics in the United States. They have been used for many years as food packaging films and as fibers for clothing, carpeting and tire cord, and more recently as beverage container resins. Most of this latter use has been in the packaging of carbonated beverages, specifically for the family-size non-returnable container.
Poly(ethylene terephthalate) is well suited to such use because it is resistant to shattering and is lightweight.
The processing of poly(ethylene terephthalate) requires the use of relatively high temperatures, viz., in the order of 250.degree.-300.degree. C. Such treatment imposes a severe strain on the polyester molecule which without some form of stabilization, will result in loss of color, loss of viscosity (due to molecular scission and correspondingly decreased molecular weight) and formation of acetaldehyde. All of these are undesirable results and it is necessary to take steps to inhibit such activity to the extent possible.