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 in 2 /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 compared 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.

Durability of nanosized oxygen-barrier coatings on polymers

“…23 represents the coating thickness dependence of the oxygen transmission rate (OTR) and crack onset strain and IFSS, in the case of evaporated SiO x /PET films. The OTR drops from 120 cc/day/m 2 for uncoated, 12 mm thick PET, to an optimal value equal to 2AE 1 cc/day/m 2 when the coating thickness is increased in the range from approximately 50 to 100 nm, after which it starts to gradually increase [24,164,304]. By contrast, the coating crack onset strain, related to its cohesive strength, continuously decreases with increasing coating thickness, at least up to 300 nm [164,259].…”

“…Transparent barrier SiO x coatings were originally industrialized in 1969 [61]. The very tight interstitial spaces of the Si-O lattice and broad ranges in thermal stability leads to oxygen [24,304]). Also shown is the OTR of Al/PET.…”

“…23. Effect of coating thickness on oxygen transmission rate (OTR [24,164,304], open squares; the dotted line is a fit to the data) and crack onset strain (filled dots, experimental [164,259]; line, theoretical derivation [165]), for PVD SiO x coatings on 12 mm PET. Fig.…”

Adhesion of silicon oxide layers on poly(ethylene terephthalate). I: Effect of substrate properties on coating's fragmentation process

“…A fusion enthalpy (117.6 J/g) for crystalline PET was used for the crystallinity measpecifically in the pharmaceutical and food industries. 5 In such applications, the coating integrity surements. has to be assured during the whole life-time of the package.…”

Durability in the life cycle of polymer composites

“…These materials are of considerable interest as an oxygen barrier for food and pharmaceutical packaging applications. 12 The films were processed and aged according to several procedures yielding precise, unique, and homogeneous interface structures or stress states. The second objective was to scale the above understanding to simulate recycling and predict the long-term strength of multilayer PET/SiO x composites, with attention paid to the effect of the size of the reinforcement phase.…”