A NEW METHOD FOR FABRICATING TRANSPARENT BARRIER LAYERS

The Polymer Multi-Layer (PML) process for the vacuum flash evaporation of acrylic monomers has been combined with conventional oxide sputter ing and evaporation processes to produce multilayer barrier coatings i n a vacuum web coating process. Polymer/oxide/polymer layers have been deposited on 2 mil polyester substrates. For a 1 mu m polymer layer o ver the substrate, followed by a 255 Angstrom Al2O3 layer capped by a 0.24 mu m polymer layer, O-2 permeation rates were below 0.0155 cc m(- 2) (24 h)(-1) and H2O permeation rates were less than 0.0155 g m(-2) ( 24 h)(-1). These exceptional permeation rates are believed to result f rom the substrate smoothing effect of the initial polymer layer. This layer eliminates substrate defects, prior to deposition of the oxide l ayer, and permits the oxide layer to grow with a minimum of pinholes. The capping polymer layer protects the oxide film during wind-up and s ubsequent handling.