HYDROCARBON FILMS INHIBIT OXYGEN PERMEATION THROUGH PLASTIC PACKAGINGMATERIAL

Pure plastic films are often too permeable for many packaging applicat ions. In these cases, the deposition of a thin functional layer can ac t as a barrier for gases and water vapour. Glassy, transparent coating s like SiOx have demonstrated their ability to provide good permeation protection but since they are brittle, handling damage can occur. The development of more flexible diffusion barrier layers is, therefore, needed. Thin hydrocarbon coatings were deposited onto plastic films by de magnetron sputtering processes carried out in non-pulsed and in bi polar, pulsed, operating modes. The influence of the process parameter s such as power, pulse frequency, process gas, working pressure, and b ias voltage on the properties of the coatings was studied systematical ly for optimization. The C:H-barrier layers are amorphous, and their s toichiometry varies between C1H0.2 and C1H0.2. Hydrocarbon layers inhi bit oxygen gas permeation up to an improvement factor of about 120, wi thout affecting the recyclability of the plastic films. Moreover, this barrier type widens the application field for transparent packaging d ue to its intrinsic flexibility. (C) 1998 Elsevier Science S.A.