The PET films used for packaging are biaxially oriented films that are stretched. PET biaxially oriented films use PET particles extruded at a melt temperature of 250-300 ℃, cooled at 60-80C, then stretched 2.54 times at a longitudinal stretching temperature of 80-90 ℃, and then stretched 2.54 times at a transverse stretching temperature of 95-115 ℃. They are then heat set at 150-230 ℃ under the tension during stretching, and cooled to form biaxially oriented PET films. The characteristics of its membrane are as follows:
① Has high transparency and luster, with a light transmittance of up to 90%;
② Outstanding initial strength, its tensile strength is three times that of PC film and nylon 6 film, its impact strength is 35 times that of BOPP film, and it has excellent resistance, folding resistance, pinhole resistance, and tear resistance.
③ The thermal shrinkage is extremely small, with only 1.25% shrinkage after 15 minutes at 120 ℃.
④ PET has good anti-static properties and is easy to vacuum evaporate aluminum. For PET that requires airtightness, it can be coated with PVC. KOPET has good heat sealing properties and improves the adhesion of PET orientation film to printing ink. Otherwise, the stress resistance of printing ink can result in good printing accuracy.
BOPET film can be used for food packaging that is resistant to heat, freezing, and disinfection. Fruits and vegetables can be packaged with PET film and stored for one year under 17C; PET is also used for packaging electronic components; PET, as a surface material for composite film packaging, has good boiling properties. A PET film with a thickness of 0.0127mm can be produced, and its yield tensile strength can reach 286.8MPa. It can be used for ovens and heat sealed packaging, and has good gas resistance, moisture resistance, and oil resistance at 204.4 ℃ (400F).
