Flat and Blown film
With the blown film process, film can be produced with a thickness of between 0.02 and approx. 1 mm. The addition of functional concentrates (e.g. antiblocking agents) or the use of a supporting foil facilitates the entire handling process.
Fig. 5 shows a blown film line.
Fig. 5: Blown film extruder
A range of fabrics such as knitted fabrics, felts and non-woven materials, as well as other materials such as paper, foils and plastic sheets can be coated with Desmopan® or Texin™ in the extrusion process. A slot die is used to apply the TPU film directly onto the substrate. A calender or impression roller is used to smooth out the melt film, which is still plastic, and bond it to the base.
The adhesion of TPU to different substrates depends on the material and/ or the surface design. Pretreating the substrate can improve the compound’s adhesive properties. If there is insufficient adhesion, applying the adhesion promoter Desmomelt® by coextrusion is often a cost-effective alternative. The adhesion promoter is applied to the web being coated by coextrusion.
Fig. 6 shows a blown film extruder.
Fig. 6: Extrusion coating plant