The availability of PC in a variety of textures give the film built-in resistance to abrasion without the assistance of a hard coat, although there are hard-coated PC options available for additional durability. PET, on the other hand, must be hard-coated to endure normal use and is available in several textures. Polyester also offers a more consistent gloss and textured surface. Once it has the coating, however, it is much harder to scratch than regular PC.
The efficacy of PET to resist chemical abrasion largely surpasses that of PC. PET is chemical resistant to household cleaners, graffiti-resistant, resistant to alcohol and acid, and overall has a greater resistance to a broader range of chemicals than polycarbonate. PC does have chemical resistance but it is limited, and overall is less desirable for harsh environment use. Hard-coated PC, however, will resist periodic first surface exposures, but this will only slow down the effects of long-term exposure that will attack uncoated edges and penetrate the hard-coating.
While most PET films do not present a significant flammability hazards, most will burn when placed under suitable conditions. PC is generally regarded as “flame-resistant”, and there are even flame-retardant films that have been designed specifically with excellent flame-resistant thermal, electrical insulation, and mechanical properties.
Visual appearance is where PC vastly overshadows PET. PC is available in a much a wider range of thicknesses and textures and finishes, such as gloss and matte versions of fine, suede, and velvet surface textures. It is also more clear than PET in higher thicknesses, allowing more vibrant colors and closer PMS color matches. While both have the same gloss level selections of 100, 90, 75, 66, 40, 35, and 20%, PC has the edge cosmetically. A variety of options can be hard for designers and marketing teams to resist.
Ease of Production
PET is harder than PC to process. It needs stabilized to resist shrinking during low temp ink curing conditions, and is more prone to splitting at the edge than PC. PET also has a higher material memory, meaning that its elastic properties want to go back to its original shape after being embossed. To emboss PET correctly high temperatures and dwell times are necessary to force it to keep its shape. While you will not see the effects of processing directly in your finished part, it will affect the lead time from your supplier, as PET parts will often take longer to make, and because PC is so much easier to work with, it often equates to lower costs.