AKRON—Groupe Michelin, responding to regulatory restrictions on suspected carcinogenic or toxic materials, will phase out the use of aromatic processing oils at its plants worldwide by the end of 2010 and is looking for alternatives for zinc oxide.
Michelin´s volunteer action goes beyond regulations in Europe that mandate tires sold in the European Union after 2009 be free of aromatic oils, according to Terry Gettys, president of Michelin Americas Research and Development Center in Greenville, S.C. He spoke on the subject while giving the keynote address at the recent Tire Society meeting in Akron.
Aromatic oils, used in rubber compounding—especially in the compounding of solution SBR with silica—contain small quantities of polycyclic aromatic hydrocarbons, some of which are classified as carcinogenic. Aromatic processing oils have a positive effect on grip and braking, Michelin said.
To effect this change without impacting current tire performances and with as little disruption as possible to its manufacturing operations and processes, Michelin began researching alternatives on its own and with suppliers in the late 1990s.
The substitutes Michelin is testing—so-called "non-aromatic oils"—contain around 50 times less PAH than do traditional oils, the firm said in a recent Performance and Responsibility document.
Even as it moves to do away with aromatic oils, Michelin said the substances are classified as dangerous only as raw materials and that toxicity has not been proved after they are incorporated into a rubber compound.
"Our research programs aiming to eliminate them are responding to a principle of precaution," Michelin wrote in the document.
Michelin also said it is studying ways to reduce its use of zinc oxide as a vulcanization accelerator, because zinc salts—which are soluble in water—are considered a toxic substance. Zinc oxide represents about 1 percent of a typical passenger tire tread compound, and the zinc is deposited into the environment as tires wear down.
Michelin estimates the equivalent of 4,500 metric tons of zinc is deposited in Western Europe each year. The solutions being considered reduce zinc oxide use by 50 to 80 percent, Michelin said.
The tire maker also said a lengthy validation program will be necessary to confirm that tires made with these alternatives are as reliable and safe as the products they replace and to market them on a large scale.
Michelin did not comment on the cost of conversion, but the European rubber industry trade group BLIC (Bureau de Liaison des Industries Caoutchouc) estimates the cost to manufacturers in Europe could be several hundred million dollars.
The European Commission, which issued the directive banning the oils, estimated that cost at less than $75 million.