Cellophane is a thin, transparent film made of hydrated cellulose. The term cellophane, which has become commonly used over time, was created by the inventor of this material, following the union of the words “cellulose” and “diaphane” (from “diaphanous”, which allows light to pass through and allows you to see through it).
Production: the VISCOSA process
Cellophane is a revolutionary material invented by the Swiss chemical engineer Jacques Edwin Brandenberger in 1908. Initially, the manufacturing process involves the regeneration of the cellulose (or VISCOSA process).
In this process, the cellulose, first treated with sodium hydroxide, and then with carbon sulfide, gives the xanthogenate (or xanthate) of cellulose, in liquid form. This ester, dissolved in alkali, is then “matured”: during this phase the liquid increases considerably in viscosity and a colloidal product called viscose is obtained. The latter is then extruded through a thin chain placed in an acid bath, so as to have the coagulation of the material in the form of film, called cellophane.
The viscose can also be extruded in the form of threads, obtaining in this case the textile fibres of viscose rayon.
During this process, the cellulose macromolecules are shortened, thus reaching lower molecular weights that lead to a loss of properties compared to the initial ones. On the other hand, however, cellulose can thus be used for higher value applications.
Cellophane properties and applications
Cellophane is a widely used packaging material, as it has properties of resistance to air, moisture and microorganisms.
Its industrial production began around 1920 and continues to the present day, even for higher value applications. Today, in fact, cellophane is used not only for packaging, but also for the production of semi-permeable membranes, used in the medical field for dialysis, and adhesive tapes.
However, especially in recent years, cellophane has been replaced in its applications by polypropylene, as it is less expensive.