Clear packaging films offer consumer product goods manufacturers the distinct advantage of allowing the customer to see the actual product before buying it. Until recently, however, the use of clear polyester films was largely limited to products not especially sensitive to oxygen andor moisture because those films simply could not offer the barrier properties of foil, metallized films, or ultrahighbarrieroriented polypropylene. In the past, clear barrier film options with a low moisture vapor and oxygen transmission properties were polyvinylidene chloride pvdc or silicon oxide siox coated films. Other means of getting oxygen barrier were converterapplied ethylene vinyl alcohol evoh copolymers.
