What is a Polyester Base Film and how is it made?
Every type of window film uses a base polyester film as its foundation.
Polyester film is produced from the polymer Polyethylene Terephthalate, or more commonly known as PET. PET is manufactured by combining terephthalic acid and monoethylene glycol, which are derived from petroleum feedstocks or resins.
Once polymerization is completed, the next manufacturing step is for the polymer to go through an extrusion process. The polyester polymer grades are extruded onto a casting drum to give the plastic film a smooth surface.
Base Film Extruder
At this point, the film is stretched in forward and transverse directions using tension
and temperature to ensure optimal quality. The film's forward draw is over a series of precision motorized rollers while transverse or sideways draw uses diverging clips in
a multiple zoned oven with tightly controlled temperatures.
As the film is being stretched, sophisticated scanners and control systems monitor the heating, cooling and coating of the film. Once cooled, the film is wound into large master rolls and can be slit to precision widths before delivery to customers. Polyester base film thicknesses typically range from 1 micron to 350 microns.
Polyester Base Film Benefits
PET films are used successfully in a wide range of applications other than window film due to an excellent combination of optical and physical characteristics. Although the final product is quite thin, polyester base films have unequaled strength and toughness while providing excellent stability when exposed to various temperatures, moistures and solvents during the window film manufacturing process.