What are the characteristics and applicability of the flat film method and the tubular film method in the production of biaxially oriented films?

What are the characteristics and applicability of the flat film method and the tubular film method in the production of biaxially oriented films?


There are currently two main methods for the production of biaxially oriented films. The tube film method involves extruding a tubular parison from an extruder, which is then blown laterally and stretched longitudinally to form the film. This method usually results in poor thickness accuracy and low production efficiency, but requires less equipment investment. It is generally limited to the production of special varieties such as PP heat shrinkable films and cigarette packaging films.
The flat film method involves casting a sheet through extrusion and then stretching it longitudinally and laterally on a tenter frame, followed by heat setting to produce biaxially oriented films. As shown in the figure below, this is the production line for biaxially oriented films using the flat film method. The films produced by this method have high thickness accuracy and high production efficiency, and are mainly suitable for various composite film substrates, electrical films, and various packaging films.
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