The Essential Handbook of Polymer Terms and Attributes

61 Film Blowing

DOI: 10.1201/9781003161318-61

Film blowing (or blown film extrusion) is a common process to make plastic films, especially for the packaging industry. The process involves extruding a relatively thick tube, which is then expanded or blown by internal air pressure to produce a relatively thin film.

The film blowing process is one of the oldest polymer processing techniques. In the late 1930s, the first commercial film blowing line was built in the United States.

In the film blowing process, the polymer is melted in an extruder and the hot melt is pumped through a die to form a thin-walled tube, which is simultaneously axially drawn and radially expanded. In most installations the extruders are horizontal, and the blown film ...