Aluminum foil is widely regarded as the most effective barrier material in flexible packaging, giving almost perfect protection against light and suppressing any transport of matter. Foil is usually converted to flexible packaging laminates by traditional converting processes, such as 2-component adhesive lamination, but more and more extrusion coating and extrusion lamination are being used.
Almost all aluminum is put through an annealing process, to produce an appropriate surface, which is as good and homogeneous as possible with regard to unwinding properties (at high speed), wettability, adhesion and chemical resistance. Solvent-based adhesive for foil lamination with good wettability.
Looking at flexible packaging, there is a distinct trend towards the use of extrusion coating and extrusion lamination for converting aluminum foil. A number of substantial benefits can be gained from manufacturing without solvents, achieving high line-speed, saving space for drying channels, saving on investment for solvent equipment or saving storage space for crosslinking adhesives and cutting lead times. The main reason for using aluminum foil in flexible packaging lies in the need to completely suppress migration or permeation through the package and shield the packaged good from the environment in the most suitable way.
