To improve the adhesion of the coating film on a poly ethylene terephthalate (PET) sheet, surface modification of the PET sheet was implemented by applying atmosphere pressure plasma processing utilizes a cylindrical shaped rotary electrode. After processing in the following conditions : (He : O2
=99 : 1, rotating speed 5.2m/s (φ
120mm rotary electrode), machining gap 500μm, RF power 300W, scanning speed of worktable 300mm/min, machining time 30sec), the existence of the hydrophilic group (-C-OH,-COOH) which contributes to the wettability of the PET sheet was observed, and surface texture which contributes to the anchoring effect was obtained.
The peel strength of the coat film on the PET sheet was also improved sharply without a surface treatment by an organic solvent.