Blown Film Extrusion Process – Tuftane® TPU
Permali manufactures and extrudes a wide variety of Tuftane® TPU films in-house to a variety of technical specifications and applications.
We’ve provided TPU film to isolation units in hospitals, for tent windows and a wide range of other specialist manufacturers all to their requirements.
As a process, blown film extrusion requires speciality expertise and knowledge to provide compliant and high-quality materials to industries such as aerospace and healthcare, where specific requirements quite literally affect lives.
There is also a need for space and modern machinery to be able to extrude, slit and roll the TPU to specifications, something that Permali is able to supply up to 1600mm @ 250 microns or 900mm @750 microns.
Blown Film Extrusion Process
Blown film extrusion begins by choosing the correct grade needed, whether polyester TPU grade or polyether PU grade.
The polymer melt is then fed into the blow machine where the correct die has been chosen whether spider, crosshead or spiral. Once fed into the die, air is blown through the middle and the polymer feeds around it, creating a long cylindrical tube of TPU. This is then cooled through a series of air blowers.
At first, the TPU film becomes an amorphous viscoelastic solid before it hits the frost line, where it hardens further and becomes a semi crystalline solid. Permali offers a range of pigments and speciality additives that can be used as required on the blown film.
Then, when it is a solid, the film is drawn through a series of rollers to bring it to the desired thickness, deflating in the process. Once at the desired thickness, it is slit and rolled onto a roller, where it can be shipped out.