Blown Film Extrusion
Blown Film (BF) extrusion is a converting technique for the mass production of flexible packaging. Film thickness can range from less than 10 microns up to 200 microns (above 200 micros it is called sheet). The blown film can be either a monolayer or a multi-layer with up to 11 layers.
The molten polymer is extruded upwards into a tube which is inflated with air and blown to the desired size. depending on the application the final film the tube can be slit to a flat film.
Depending on the final applications different grades are being used. The thinner the film, the higher the Melt Flow Rate (MFR) needed, which is a measure for the viscosity of the molten polymer.
Polyethylene (PE) and polypropylene (PP) are the most widely used resin for Blown Film extrusion.