Milliken Chemical at NPE 2003 touted an additive that dramatically could improve the shelf life of beverages, vitamins and other ultraviolet-light-sensitive products packaged in PET containers.
PET containing ClearShield provides up to 10 times as much UV protection as standard PET, depending on the contents, said market manager Mike Purcell. It does not affect taste, color or clarity.
Purcell said ClearShield is a liquid polymer that blocks all UV rays up to 390 nanometers, providing high protection without the use of pigments. Since it is highly compatible with PET it does not extract out, or bloom. He would not disclose the basic chemistry of the additive, but said it is different from standard UV absorbers such as benzotriazoles or hindered amines. It appears to be benign in PET recycling processes, he said.
``A universally accepted standard for UV protection has not emerged within the industry due to a lack of understanding about the effects of UV on beverage ingredients,'' Purcell said. ``Our research has shown that any level of exposure to UV rays can impact the color, flavor, aroma and nutritional value of beverages, and the only way to be certain of eliminating this product-quality concern is by blocking all UV rays with 390 protection.''
PET resin producer KoSa of Houston has two commercial PET grades containing ClearShield, Purcell said. The additive has potential in other polar polymers such as nylon, but is not suited to polyolefins, where it is likely to bloom. Milliken is aiming it at packaging applications, but not at uses where there is long-term exposure to UV light and weather.