A multilayer polyester film, and a method for making the same, is provided. The film consists of alternating layers of polyethylene terephthalate and polyethylene naphthalate. Biaxial orientation and subsequent restrained heat setting of these materials results in thin films with tensile moduli in both...http://www.google.ca/patents/US5968666?utm_source=gb-gplus-sharePatent US5968666 - Multilayer polyester film
