1. Bi-directionally oriented polyester film (BOPET) is a kind of high-grade film with high strength, rigidity, transparency and luster, which is made by adding titanium dioxide into the original polyester chip, through drying, melting, extrusion, casting and longitudinal and transverse stretching. BOPET film has the characteristics of high strength, good rigidity, transparency and high gloss. Taste, colourless, non-toxic, outstanding strength and toughness; its tensile strength is three times that of PC film and nylon film, impact strength is three to five times that of BOPP film, with excellent wear resistance, folding resistance, pinhole resistance and tear resistance; thermal shrinkage is very small, at 120 C, shrinkage is only 1.25% after 15 minutes; it has good antistatic property and easy to stop. Vacuum aluminium plating can coat PVDC, thus improving its heat sealing, barrier and printing adhesion; BOPET also has good heat resistance, excellent cooking resistance, low temperature freezing resistance, good oil resistance and chemical resistance. Except for nitrobenzene, chloroform and benzyl alcohol, most of the chemicals in BOPET film can not dissolve it. Therefore, it is of universal use.