Effect Of Preparation Process On The Adhesion Strength Of SiO₂/PET Composite Packaging Films

SiO₂/PET composite packaging film is a new type of flexiblepackaging material, it has intrinsic characteristics, such as: excellentbarrier properties, good transparency, boiling resistance, microwave andenvironmental protection. Because of these advantages, it is widely usedin food, medicine and daily chemical, etc. In this paper, SiO₂/PETcomposite packaging film was prepared by depositing SiO₂on PETsubstrates through magnetron sputtering technology, the state of SiO₂particles and its dispersion properties in PET matrix were characterizedby scanning electron microscopy （SEM）, energy dispersive spectroscopy（EDS） and adhesion strength tester. During the process, the effects ofsubstrate cleaning process, sputtering process parameters andintermediate layer on the bonding strength of the coating-substrate systemwere investigated systematically.Firstly，the effects of different cleaning techniques of PET substratesand process parameters of plasma cleaning on the bonding strength of thecoating-substrate system were studied. The results showed that:（1） thebonding strength of coating-substrate system after plasma cleaning wasincreased by7.83%,27.27%and55.56%compared with that of the deepcleaning, general cleaning and no cleaning, respectively;（2） in plasmacleaning process, the bonding strength firstly increased and thendecreased with the increase of cleaning time, radio-frequency power andargon flow. The bonding strength of coating-substrate system was up to amaximum at the argon flow of25mL/min, cleaning power of200W andcleaning time was300s.Secondly, the effects of the radio-frequency power, sputtering time,argon flow and local vacuum on the bonding strength of thecoating-substrate system were studied. The results showed that:（1） thebonding strength firstly increased and then decreased with the increase ofsputtering time, radio-frequency power and argon flow;（2） the bondingstrength of coating-substrate system increased with the increasing localvacuum;（3） in the four process parameters，sputtering time had thegreatest effect on bonding strength, followed by radio-frequency power, local vacuum and argon flow;（4） the optimal process parameters wereobtained: radio-frequency power of200W, sputtering time of90min,argon flow of20mL/min and local vacuum of1.5×10^-4Pa.Lastly, the effects of interlayer on the bonding strength of thecoating-substrate system were studied. The results showed that:（1） thebonding strength of coating-substrate system was improved by depositingAl₂O₃interlayer between SiO₂film and PET substrates;（2） the optimalvalue of film thickness existed. The maximum of bonding strength ofcoating-substrate system will not be obtained with a larger or smallerthickness.