What are the Requirements for Using Aluminum Foil as a Functional… by: Packaging Law at Keller and Heckman.
I understand that the inclusion of an aluminum foil layer in laminate materials is considered by FDA to be a functional barrier.
Should the aluminum foil layer have a minimum thickness to be considered a functional barrier for printing ink? Or does the aluminum foil layer thickness not matter if it has PET layers laminated on both sides?
Under Section 177.1390, FDA does consider aluminum foil to be an effective barrier to migration of materials used on the non food-contact side of the foil, and the regulation does not specify any minimum thickness of the aluminum foil layer.
Notably metallization does not constitute an “aluminum foil” layer.
The metallized plastic must itself be a functional barrier.
You mentioned PET layers may be applied on both sides of the aluminum foil.
At a thickness 50 µm at higher temperatures, including use as a dual-ovenable container for cooking food at 150°C for 30 min, provided that only food containers are used in the feedstock to manufacture the recycled layer.
Although this guidance is provided in the context of recycled plastics, it suggests FDA considers PET layers specifically meeting the thickness criteria above will serve as a functional barrier to prevent migration of substances from the non food-contact side under the stated conditions of use.
Layers made from other, non-PET polymers must be assessed on a case-by-case basis, through testing or mathematical modeling, to determine whether they may be considered a functional barrier in the application of interest.