Calenders invention

The elimination of facial flow marks and pits is accomplished by manufacturing technology rather than formulation. In the invented method, film from the calender directly enters a water bath tank which partially cools material and crystallizes it. Material then passes a set of pressing rollers which preferably include 3 sets of rubber/metal rollers. 

Invention describes the use of plasticizer to dissolve resin. A solution of resin is mixed with graphite to form a mass, which, after the process of calendering, forms a film or a sheet. The formed material is subjected to a temperature sirfficiently high to remove the plasticizer by evaporation (250°C). After the plasticizer (diallyl phthalate) is removed a sheet is subjected to temperatures between 500 and 1000°C imder nitrogen atmosphere which decomposes the resin and leaves a fully carbonaceous diaphragm. Other similar processes were discussed in Chapters 11 and 13. In many cases, the plasticizer is also removed by extraction with a suitable solvent. 

The best known characteristic of factice, before the invention of partially crosslinked Superior Processing grades of NR and their synthetic equivalents, was the property of conferring dimensional stability to extruded and calendered stocks. Extruded items such as tubes, hose, cables and automotive window seals must retain their configuration during vulcanization either in open steam or during vulcanization by low-pressure processes such as LCM. In this area factice acts as a non-thermoplastic additive. 

In 1798, Nicolas Louis Robert invented the paper machine. It took more than fifty years, however, until calenders were installed in the paper machine. These calenders - also called machine calenders - consisted of at least two hard rolls. A decade later the supercalender appeared with a large number of alternating hard... 

---