LONDON—Work is advancing toward replacing the key synthetic rubber monomer, oil-derived isoprene, with a green substitute.
Researchers have developed organisms that feed on plant matter and use the energy to grow and multiply, in the process converting a proportion of the energy into isoprene monomer. They expect in the future that new organisms will produce other monomers, such as butadiene.
Less than two years ago Goodyear announced it had partnered with the Genencor division of Danisco A.S. to develop a bio-based process for producing isoprene using renewable raw materials. Called BioIsoprene, the alternative for the petroleum-derived chemical compound is used to produce SR and other elastomers.
Goodyear, at the time, said the chemical could make the tire and rubber industries less dependent on oil-derived products. The company invested in research done at Genencor's laboratories in Palo Alto, Calif., to validate the project, establish teams and secure intellectual property assets.
Since then a second bio-engineering company, GlycosBio, began setting up a plant in Malaysia to make isoprene monomer. And another firm, Arzeda, has begun research to develop an organism that can produce butadiene.
The vision is a system that can sustainably produce these monomers, which then feed into more conventional rubber factories to make elastomers. These elastomers should be indistinguishable from SR made from oil-derived monomers.
Currently, the world consumes about 850,000 metric tons of isoprene monomer each year. About half is used in Russia to make polyisoprene for tires, while Japan utilizes a large percentage, too.
The rest of the world primarily uses natural rubber instead.
The second-largest market is for block co-polymers used in applications such as hot-melt adhesives.
Isoprene also is used in small quantities for the production of butyl rubber (isoprene-isobu-tylene rubber) and a fast-growing application is in hypoallergenic gloves and condoms, as a replacement for NR.
The Goodyear-Genencor project is ahead of the initial time projections, said Jesse Roeck, Goodyear director of material science. Overall the project is expected to cost about $50 million over three years to 2011, although Goodyear's financial commitment hasn't been disclosed.
Roeck said the current project is to look at a living microbe. “We are doing trans-genetic modification of that microbe from genes in different parts of the universe and teaching the bacterium to produce isoprene,” he said. Genencor has said the microbe is based on E. coli.
Dave Benko, director of materials research and development at Goodyear, said the company has made three tires using the material. Those tires used a tread compound made from Bio-NatSyn, Goodyear's trade name for its synthetic polyisoprene, but the rest of the tire—carcass, sidewalls, etc.—was made from conventional materials.
Roeck said the elastomer in the tread compound was entirely Bio-NatSyn, although other ingredients such as carbon black were used in the compound.
“When you can produce a tire, that is a big demonstration of technical feasibility,” Roeck said. “When you can make enough of it, collect it, polymerize it and be able to formulate that into a rubber compound and make a tire, it really demonstrates that the pro-ject is moving along.”
The tires were shown at a Copenhagen exhibition, and just intended to de-monstrate it could be done, not to ever be used on a vehicle, Roeck said.
“We are looking to go commercial in about five years. We will be doing research to continue to improve yield and efficiency until then.”