A 100%, petroleum-free tire?! Sounds like a fantasy, doesn’t it? Sumitomo Rubber Industries Ltd. doesn’t think so.
Earlier today at the International Tire Exhibition and Conference (ITEC) in Akron, Ohio, Sumitomo’s Mamoru Uchida presented an overview of how his company has reduced the content of oil in a tire by 46% in its Dunlop ENASAVE ES801, the “next generation environmentally friendly tire.” And it’s a tire in production, not just a concept tire.
“Tires are made from around 100 different kinds of material,” he said. “Of this number, the four main petroleum materials are synthetic rubber, carbon black as a filler, mineral oil and synthetic fiber for the casing.
“The Dunlop ENASAVE ES801 tire reduces the use of synthetic rubber by increasing natural rubber, and utilizes natural materials for filler, oil and casing. This has successfully raised the proportion of non-petroleum materials from 44% for our conventional tires, to 70% for the ENASAVE ES801.
“The increased use of these materials has also lowered rolling resistance by 30%, contributing to improved fuel.”
His speech, "Development of the Petroleum-Free Tire,” is excerpted below.
Introduction
The fundamental functions which are required from a tire are as follows:
* to support the vehicle load.
* to absorb shocks from the road surface.
* to transmit traction and braking forces to the road surface.
* to change and maintain direction of travel
To realize these functions, around 100 kinds of material are used in a tire. These materials were improved in their performance with the progress of vehicle technology starting from the Model-T Ford, the development of expressway service, the development of petrochemistry and a certain number of inventions regarding tire technology such as the pneumatic tire and subsequently the radial tire.
Today, petroleum materials account for over 50% of the materials by weight which are used in a tire.
Petroleum materials are taken into confidence for tire technology due to their special characteristics. Therefore, tire performance has been able to follow the progress of vehicle technology.
On the other hand, there is an anticipation that oil supplies will dry up and also the considerable consumption of oil is responsible for many environmental issues.
Product concept: ENASAVE ES801
We considered the following two approaches to make our contribution to this environmental issue. One is to increase the usage of petroleum-free materials and the other is to reduce a tire’s rolling resistance for reduced fuel consumption.
1. Substitution of materials. The usage of material for the standard and the petroleum-free tire ENASAVE ES801 is as follows. The weight ratio of petroleum-free material is raised from 44% to 70% by replacing synthetic rubber with natural rubber, carbon black with silica, mineral oil with vegetable oil and synthetic fiber with vegetable fiber.
The substitution of rubber is important to the weight ratio of petroleum materials and tire performance. When the substitution of rubber is made at the tread compound, then the tire performance is degraded with respect to grip.
Natural rubber has the characteristics that its grip performance is inferior to that of synthetic rubber SBR when applied in a tread compound.
Natural rubber has a longer molecular chain but compact side chain compared with synthetic rubber SBR; therefore, natural rubber shows better rolling resistance but less grip performance compared with synthetic rubber SBR.
Since grip performance, especially wet grip is important for safety… we applied a modified natural rubber to improve grip performance.
2. Modified natural rubber tread compound. An epoxidized natural rubber, which is one of the modified natural rubbers, shows a change of the loss tangent curve and is close to that of synthetic rubber SBR.
With the combination of epoxidized natural rubber, silica and vegetable oil, we are able to produce a tread compound which is competitive to a synthetic rubber tread compound in grip performance.
3. Tire design. The new concept tread pattern design is effective in the reduction of rolling resistance, with good wet grip, dry handling and noise reduction on ENASAVE ES801.
Compared with the standard tire, ENASAVE ES801 can achieve a 30% reduction of rolling resistance and better performance in all other criteria.
Conclusion
The first pneumatic tire made in Japan was launched in 1913. In this tire, the tread compound was composed of natural rubber and magnesium carbonate together with other materials that were considered as petroleum-free materials.
We continue to develop the petroleum-free tire aiming at this first pneumatic tire made in Japan as the target of petroleum-free materials ratio but with the excellent tire performance properties required from a modern day product.
