Transparent Gas Barrier Technologies

Abstract

Transparent gas barriers are receiving considerable attention in the plastics industry for roll coating applications. The three principle vacuum deposition processes, evaporation, sputtering and plasma processing are the focus of transparent gas barrier work at various converters, resin producers and equipment manufacturers. Evaporation produces coatings at very high rates, but plasma processing has reported the best gas barrier results to date [ < 0.06 cc/100 in²/day for single-sided coatings on 0.5 mil polyethylene terephthalate (PET)]. Sputtering rates are lower than evaporation rates, but can produce a wide range of transparent oxides including the material of interest, silica. Evaporated, sputtered and plasma deposited coatings were produced and com pared in terms of oxygen gas transmission and film stoichiometry. The plasma deposted coatings provided the best gas barriers and initial results show that the plasma processed barrier coatings are commercially feasible.