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Coextrusion and Coatings Provide Choices for Clear Barrier Packaging

While many flexible packaging films offer product visibility, not all clear films provide the oxygen and/or moisture barriers required to maintain freshness and flavor. One of the most commonly utilized elements of transparent barrier films is ethylene vinyl alcohol (EVOH). A strong barrier to oxygen with high sensitivity to moisture, EVOH is incorporated into multilayer films to combine barrier, structure, and sealing properties needed for a given application. Specialty coatings, on the other hand, improve a film's performance by adding the effect of the coating applied. Coating a polyester (PET) film with polyvinylidene chloride (PVDC) yields KPET, a clear flexible material with all the benefits of PET and improved oxygen barrier performance. Coating with silicon oxide (SiOx) or aluminum oxide (AlOx) provides high barrier properties in a thin, flexible, transparent format. 

Selecting a clear barrier film demands review of product and process needs. While AlOx and SiOx films offer tremendous barrier properties, the coatings can experience flex cracking under extreme stress, which can reduce barrier performance. 

Films coated with PVDC offer excellent resistance to cracking, however, they can pose environmental concerns as chlorine present in the structure can yield harmful vapors in common municipal incineration processes. 

While immune to cracking and lower in cost than coated films, EVOH based films require greater thickness to provide equal barrier performance. To learn which film is right for your application, contact Flair today!