Oxygen Gas Barrier PET Films Formed by Deposition of Plasma-Polymerized SiOx Films

摘要

In order to prepare SiOx-deposited PET films with a high oxygen gas barrier capability, SiOx depositions from the plasma polymerization of silane compounds have been investigated from viewpoint of the chemical composition of the deposited SiOx films and oxygen permeation rate through the SiOx-deposited PET films. Tetramethoxysilane (TMOS) was suitable as a starting material for the SiOx deposition from the plasma polymerization. Oxidation and etching processes by selfbias effects were effective in the SiOx deposition. The SiOx film deposited on PET film surfaces from the TMOS/O_2 mixture (60 mol% O_2) was mainly composed of Si-O-Si networks with a carbonized carbon component as a minor product. The SiOx-deposited PET film showed good oxygen gas barrier properties. The oxygen permeation rate was 0.10 cm~3/m~2-day-atm, which corresponded to an oxygen permeability coefficient of 1.4 x 10-17 cm~3-cm/cm~2-sec-cmHg for the SiOx film itself. This permeability coefficient is three orders lower than that of conventional gas barrier polymeric films such as Eval and Saran.