Bonding of extruded PET to aluminum foil with adhesive primers present unique technical issues compared to polyethylene. We have determined thatthe heat transfer from PET to the foil can be instantaneous leading to a precipitous drop in the temperature at the PET / foil interface. If this temperature drops below the glass transition temperature of PET, poor bonding will result. Polyethylene, by contrast, has a lower glass transition temperature than PET. The temperature of the melt at the polyethylene-aluminum interface does not go below the glass transition temperature, making bonding on thick aluminum substrates easier. A model for the heat transfer and a relationship that establishes the minimum PET thickness for good adhesion to foil are presented.
展开▼
