Mylar® is a registered tradmark of DuPoint name for Biaxially-Oriented Polyethylene Terephthalate (BoPET). While most people are familiar with the shiny silver balloon material called Mylar, the material itself is clear and produced by stretching PET plastic film. It's high tensile strength and chemical stability make it a popular material for packaging. While it's unbiquity has made it a common term for plastic or PET films in general, Mylar® remains a DuPoint branded stretched PET film that is manufactured into a variety of forms.
indsutrial machines that pul and press material structures together into a film roll

So What is MylarFoil?

As mentioned, a lot of people's first encounter with Mylar is of a version that contains a metalized foil layer adding a reflective sheen to the film. This is a thin Vacuum Metalized layer that adds both a nice metalic look, and increased barrier protection to the Mylar base. This MylarFoil structure has become an industry standard from the afformentioned printed ballooons, to large box liners for industrial shipping. Unlike traditional foil filmstock like what you would see used in old Ketchup packets, the foil layer in MylarFoil is inmcredibly thin - allowing for a more felxible and puncture resistant material with extremely high Oxygen and Moisture barrier properties. The smooth PET top layer is resistant to both oils and solvants (no staining or rust even with MylarFoil), making it a reliable material to use in a wide variety of environments.
chemical drawing of BoPET material structure

Chemical Structure of BoPET Mylar

White printed on mylarfoil material for use in medical pouch packaging
Mylar foil takes print very well for colorful or graphic product packaging like these medical packaging ready

3" x 4.5" White MylarFoil Minipouches
metalized foil mylar in an indsutrial sized side gusset bag with valve for coffee storage
High barrier makes indsutrial large scale packaging less risky - even with sensitive products like coffee beans

24" x 8" x 36" Mylarfoil Side Gusset Bags