Polyester Film Manufacturing and Technology

Below is a brief explanation of the standard extrusion process used in manufacturing polyester film.

  • Polyester polymer grades (made in continuous process or batch reactors) are extruded onto casting drum (gives ultra smooth surface to plastic film).
  • Film is stretched in forward and transverse directions.
    • Two-stage process: first forward draw is over series of precision motorized rollers, sideways draw uses clips in main multiple oven where film is heated in tightly controlled temperature zones.
    • Most advanced technology uses simultaneous forward and sideways draw.
    • In all processes, tension and temperatures are critical to final quality of film.
  • Sophisticated scanners and control systems maintain process conditions at optimal point.
  • Advanced structures are made by extruding layers of polymer simultaneously and coating film as it is stretched.
  • Film is wound into large master rolls (can be slit to precision widths before delivery to customer).
  • Film thicknesses typically range from 1 micron to 350 microns.
  • Each asset usually designed for narrow range of thicknesses.
    • Offering complete range of films requires heavy investment in multiple lines (from $50 million up).