Abstract
Transparent Al2O3 films with high gas barrier properties were deposited on a PET film substrate by a web coating method using an activated reactive evaporation (ARE). The web speed was 100 to 700 m/min. The thickness of the Al2O3 film was 5 to 30 nm. ARE was beneficial for two reasons. One was the enabling of sound Al2O3 formation, and the other was the smooth winding of the Al2O3 deposited PET film achieved by neutralizing the negative charges, i.e., secondary electrons resulting from electron beam radiation on the Al evaporation source. The Al2O3 coated PET film showed an excellent barrier performance of about 1 g/m2 · day for water vapor transmission and about 1.5 cm3/m2 · day · atm for oxygen transmission, respectively, and an optical transmittance near to that of the uncoated PET. Results from analyses of Auger electron spectroscopy and X-ray diffraction, and observations of transmission electron microscopy and atomic force microscopy of the Al2O3 films are also described.
