Antiblocking agents are used in the packaging film industry to stop film from sticking to itself during processing, when in use, or during storage on rolls or shipped in cartons. Elevated temperature, pressure and processing time all increase the tendency to blocking.
The majority of antiblocking agents are used in LLDPE and PP films because of the very high volume produced. There is also a demand for them in flexible PVC and to a lesser extent hard film like PET.
The force resisting the sliding of two contacting film surfaces over each other is much greater when the surfaces are smooth than when they are rough. The role of antiblocking agents is to roughen the film surfaces slightly, which is achieved by the additives particles protruding out of the film surface, so that the surfaces are in contact with each other at fewer points.
Antiblock are available in the form of masterbatches. The additive must be very well dispersed in the carrier polymer to avoid having localized regions where sticking could occur.