NAPHTHENIC EXTENDER OILS IN NR TIRE TREAD COMPOUNDS

Highly aromatic oils have been the most common extender oils for natural rubber compounds for many years, especially in tires.  However, as new laws come into force in the European Union in order to deal with issues related to their carcinogenicity, the supply of highly aromatic oils will decrease and an increasing number of rubber materials will need to be plasticized with non-carcinogenic oils. Even though the change of oil is not mandatory in technical rubber goods, many producers will follow this green trend, also partly because the EU directive on tire oils has led many oil producers to revise their product offer to the rubber industry.   
In this paper, we present the effect of changing the extender oil in a truck tire tread compound based on natural rubber and compare various extender oils that meet the requirements set by EU Directive 2005/69/EC on polycyclic aromatic hydrocarbons. The contribution of different oils on processing, physical and dynamic properties of the NR compound is discussed. The results show that rubbers plasticized with naphthenic oils are very similar to those plasticized with other environmentally sound alternatives (e.g. TDAE or RAE) and that only small formulation adjustments are needed when switching from carcinogenic oils (DAE) to environmentally-sound oils like naphthenic oils.