EFFECT OF THE CAST FILM PRODUCTION PROCESS ON THE PROPERTIES OF ORIENTED POLYPROPYLENE FILM

To produce highly transparent flat film from polypropylene, the melt m ust be cooled as quickly as possible to form the cast film. With polyp ropylene, heat transfer in the cooling unit is associated with crystal lization processes. These make it difficult to calculate cooling times and subsequently the geometry of the cooling unit. A mathematical met hod for designing cooling units for polypropylene melts is described. The calculated results are compared with experimental findings and rec ommendations for optimized cast film cooling are given.