Calendering and hot-melt coating

Calendering is a popular method of rubber processing. It is also used in the production of films and in lamination of plastic film to substrates in a continuous web process. Hot-melt coating equipment is another version of calendering equipment used for production of plastic coated textile materials. 

The addition of fillers, especially fibers and platelets improves properties even further, since the filler particles are also oriented. Particle orientation can be produced by relatively small materials strain (a few percent). This is demonstrated in more detail in Chapters 7 and 10. This principle is used in the rubber industry where with simple calenders, fibers are oriented preferentially in one direction. If 

More sophisticated calenders used to coat with the thermoplastic polymers give even more control. For example, with the proper choice of conditions, metal flakes can be oriented parallel to the surface which in roofing membrane increases their ability to reflect radiation. The precision of these machines offers very broad range of possible processing conditions. 

Incorporation of fillers does not require substantial adjustment in process conditions. In fact, the process is easier in the presence of fillers because the filled material usually has a lower adhesion to the cylinders of calenders which makes it easier to process. Also, cooling times are reduced because fillers increase the crystallization rate. 

---