Slip additives reduce the coefficient of friction of a polyolefin film during critical production phases and help decrease the film's tendency to stick to the various working parts of the converter. Without these additives, the polyolefin film will be difficult to extrude to a finished product with the desired properties. As a result, most polyolefin producers apply different additives to improve slip.
In plastic bottles for beverages, slip additives are often used in the production of the screw-top lid to reduce friction. But normal slip additives can have a negative impact on the quality and taste of the beverage, especially in CO2-enhanced drinks.
Polyethylene terephthalate (PET) is widely applied in the food packaging industry. Besides its excellent mechanical and optical properties, it also exhibits very good barrier properties. However, one of the challenges of processing and handling PET is its strong surface adhesion.
Therefore, slip additives are required to reduce the coefficient of friction of the polymer surface during processing, handling and application. This enables better processibility and reduces the risk of surface defects.
In comparison to most other polymers, PET is processed at higher temperatures (280-320 ºC) and is sensitive towards hydrolysis. Owing to hydrogen bonding, migration of additives through the PET matrix is more demanding. This implements specific requirements for polymer additives used for PET, like high temperature and chemical stability during processing.
Einar® 621 is a food-grade slip additive which matches the specific requirements of PET processing. It is very stable chemically and in terms of temperature, even under demanding processing conditions. Owing to its excellent lubrication properties, PET films and injection molded items containing 1.0-2.0wt% of Einar® 621 show instantly significantly reduced surface friction.
Einar® 621 is fully compatible with fillers, which might be used additionally as antiblocking agents.