Bonding effect of plasma-irradiated PET films can be preserved after soaking in various liquid reagents

Abstract

To clarify the bonding mechanism for the plasma-irradiated PET films and the origin of the long lifetime of the bonding ability, we soaked the irradiated films in various types of liquid reagent, then tried to bond them by heat-pressing. The irradiated films do not lose the bonding ability after soaking in water, acid, alkali, and organic solvents, whereas they lose it after soaking in ionic solutions of AlCl3 and FeCl3. The COOH is created on the surface by the irradiation, but it is consumed by the chemical reaction with Al and Fe ions. This is the origin of the inactivation of the irradiated surface and the disappearance of the bonding ability after the soaking. The result supports our proposal of "dehydrated condensation reaction" concerning COOH as the bonding mechanism. The irradiated films should be stable in a normal atmosphere for a long time because they are not subjected to water, acid, alkali, and organic solvents