Abstract: The change in shrinkage of bi-axially oriented polypropylene (BOPP) cigarette pack film with temperature and time was studied. }Che thermo-shrinkage of the film decreased continuously after it was prepared, the decreasing rate in winter was lower than summer because of low temperature. A novel time-stability masterbatch was developed and introduced into the cigarette pack film. The masterbatch lowered the sensitivity of thermo-shrinkage to both temperature and time, thus retarded its decrease with time and eliminated the effect of high temperature in summer. In addition, the masterbatch did not result in negative effect on mechanical properties, gloss, haze, heat seal property, slip behavior, and processing of the film.

Key words: bi-axially oriented polypropylene, cigarette plastic film, time-stability, heat-shrinkable rate