The replacement of highly aromatic oils by naphthenic oils in rubber compounds
Anita Neau , Nynas
For many years, oils containing high amounts of carcinogenic substances have been used as plasticisers in tyres and in rubber compounds. These highly aromatic oils, the aromatic extracts, have been a favorite choice because of their low market price and their compatibility with many polymers. However, as new laws come into force in countries of the European Union in order to deal with issues related to their carcinogenicity, the supply of aromatic extracts will decrease and an increasing number of rubber materials manufactured in the EU will be plasticised with non-carcinogenic oils. When highly refined, naphthenic oils and paraffinic oils are free from carcinogenic compounds; for this reason, they have been evaluated to replace aromatic extracts in a number of applications, including rubber compounds. Naphthenic oils contain more cyclic alkanes than paraffinic oils, this gives them a higher solvent power (closer to aromatic extracts) and an improved compatibility with rubber polymers. This paper discusses the results of a study comparing the performance of naphthenic oils to that of highly aromatic oils in natural and synthetic rubber compounds.