Blocking is the adhesion of two adjacent layers of film and is a common problem encountered by manufacturers of polyolefin films and coatings.
It is thought that this circumstance occurs due to the presence of Van der Waal’s forces between molecules, named after Dutch scientist and Nobel Prize for physics, who lived in the 19th century and discovered such phenomena.
The blocking between adjacent layers results in increased friction and the addition of an Antiblocking agent generally contributes to a reduction in the film-to-film coefficient of friction.
Natural silica obtained from sedimentary rocks have always been used as Antiblocking agents, due to their structure that resembles a microscopic sponge or a very small pumice which can increase the formation of micro-wrinkling on the film, thus reducing the points of contact and giving a perfect detaching effect.
However, the natural silica performs a lower Antiblocking effect if compared to synthetic silica. Natural silica has larger dimensions and shows impurities. For all these reasons synthetic silica is preferred.
VIBA Laboratories have developed two Antiblocking additives, VIBATAN® PE ANTIBLOCKING 03946 and VIBATAN® PE ANTIBLOCKING 04251 suitable for the extrusion of polyolefin films, even of those having minimal thickness.
Both are perfectly suitable to replace Masterbatches containing natural silica which may cause unpleasant effects, such as the reduction of optical properties or the excessive absorption of co-additives, thus limiting their performance.
VIBATAN® 03946 and VIBATAN® 04251 avoid such inconveniences drastically by reducing the points of contact and giving a perfect detaching effect at a lower dosage if compared to Masterbatches having natural silica.
Both products are suggested for the production of food packaging.
VIBA’s Technical Department is at disposal for any further information you may require.