Unoriented Plastic Films
This chapter reviews the extrusion processes, cast and tubular, that produce unoriented plastic films used in flexible packaging. Basic process sequences for each process are described. The processes on the physical properties of the film have direct effects on the physical properties of the resultant films, even if the initial plastic resin on either process is essentially identical. Process conditions such as draw down ratio (DDR) and blow up ratio (BUR) cause very different crystallinity patterns in films made in the different processes. The differences at this microscopic level are evident in the different machine and cross-direction properties of the film.
Amorphous; blow up ratio (BUR); chill roll release; ...