Effect of Anti-blocking Particles on Oxygen Transmission Rate of SiO_x Barrier Coatings Deposited by PECVD on PET Films

摘要

The influence of the surface morphology of semicrystalline poly(ethylene terephthalate) (PET) substrate films on oxygen transmission rate (OTR) and on mechanical properties of ultra thin oxide coatings is analyzed, with attention paid to the role surface defects initiated by anti-blocking particles. Nanometer thick SiO_x coatings are deposited by PECVD on three grades of PET films containing predetermined surface defect densities ranging from 300 to 1800-mm~(-2). Coating failure is shown to be initiated at defect sites and leads to a decrease of the crack onset strain by a factor of 20% and a loss of barrier by a factor of 3. The failure mechanisms of coatings are determined by means of fragmentation tests and the results are modelled using a constant interfacial strength approach with a Weibull-type probability of fracture.