world thinks of plastic films, it thinks of PET.
Film Manufacturing and Technology
Below is a brief
explanation of the standard extrusion process used in manufacturing polyester
- 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.
- Sequential Draw process:
the film's forward draw is over a series of precision motorized
rollers; transverse or sideways draw uses diverging clips in a multiple
zoned oven with tightly controlled temperatures.
- Simultaneous Draw process:
the film is drawn using precision controlled simultaneously diverging,
and accelerating clips through a multiple zoned oven with tightly
- In all processes, tension
and temperatures are critical to final quality of the 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 per line).