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Thin Film Material Sourcing, Thin Film For Medical, Textiles – Sourcebook
Blown films are manufacturing using a vertical extrusion process. Similar to the cast extrusion process, selected polymer resins are first heated, melted, and extruded through an annular die. As the molten polymer is extruded through the die vertically, a cold airstream is pushed through the center of the die at the same time. As a result, the molten polymer is forced away from the center of the die, forming a bubble and shaping the film into a tube. The tube is pulled upwards and flattened into a lay-flat tube, which can be used as bags or slit to produce sheets of film.
The manufacturing process for cast films allows for more precise control of thickness, while the blown film process allows for thinner films to be produced. In addition, due to the quick quench in the cast film process, cast films have greater transparency and gloss. However, blown films are typically denser, have higher tensile strength, and better strength uniformity in the machine and cross direction. Overall, cast films are more expensive to produce than blown film, but have a faster processing time.
Packaging (thermoformable packaging)