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Thin Film Material Sourcing, Thin Film For Medical, Textiles – Sourcebook


A film is thin, plastic material composed of either one layer (monolayer) or several layers (multilayer) of different polymers that is formed through extrusion. Multilayer films are utilized in order to create a material that takes advantage of various properties of multiple polymers.
There are a number of different subtypes of flexible film materials which are derived from the manufacturing techniques used to produce them. The two most common come from the main manufacturing techniques called Cast and Blown film. Also commonly used are Aperatured, Extruded, Co-Extruded, and Embossed, which are derived from features of the Cast and Blown processes, or other downstream processes.
There are two main manufacturing methods for films: cast and blown. Cast films are manufactured through a horizontal extrusion process that begins with polymer resins being poured into an extruder, heated to their melt temperature, and then extruded through a flat die. The cast film is cooled quickly (either by an airstream or chilled rollers) and the resulting sheet is trimmed and wound.

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.

Wound care substrates
Medical bags/pouches
Bioreactor bags
Surgical films
Packaging (thermoformable packaging)