Synthetic Rubber Markets Enjoy a Bounce from Low Oil PricesYasmin Pascual Khalil | December 15, 2015
The main use of natural and synthetic rubber is for tire manufacturing. Globally, 70% of all elastomers (natural and synthetic) are consumed for tire and tire products manufacture, says Emanuel Ormonde, IHS Chemical consultant. Approximately, seven gallons of oil are used to produce enough synthetic rubber to make a tire, according to the Rubber Manufacturers Association. Recent lower energy prices result in lower costs for synthetic rubber manufacturers and higher demand as motorists drive more.
Two main areas exist where tire producers could benefit from lower oil prices, says Bill Hyde, senior director of olefins & elastomers at IHS Chemical. On the demand side, if miles driven increase, as they have in the U.S. this year, then tire wear also should increase. “We have not seen significant change in tire demand yet, but it stands to reason that it will happen, at least eventually,” he says. On the supply side, raw material prices have dropped, which has been helpful for tire producers, he says.
One difficulty, however, is that rubber producers can’t fully enjoy the decrease in raw material prices because their sales prices have fallen. What’s more, the synthetic rubber market is plagued by surplus capacity and weak natural rubber market dynamics.
Globally, tire markets are seeing diverse trends. In North America and Western Europe demand is relatively stable. In China, the tire market is something of a disappointment. “The economic conditions there have put significant pressure on the automotive and tire markets,” says Hyde. Furthermore, demand focused on the original equipment (OE) market is growing, but sales into the replacement tire market are disappointing.
Back to Basics
Tires are made by combining raw materials to ensure performance, efficiency, reliability and safety. A tire is used to cover a wheel's rim to protect it and allow for better vehicle performance. Tires provide traction between the vehicle and road while acting as a flexible cushion to absorb shock.
According to Hyde, a typical tire can contain more than 30 different grades of rubber. They are broken down into natural rubber (NR), polyisoprene rubber, polybutadiene rubber (BR), emulsion styrene butadiene rubber (eSBR) and solution styrene butadiene rubber (sSBR). Each provides different performance characteristics which are optimized in the tire design process.
The fundamental process for making a tire hasn’t changed much in the last five decades. While the compounds, components and automation used in carrying out the process have progressed, the basic process of wrapping piles of rubber and putting them in a press to fashion the finished product remains the same.
The production process begins with the selection of different grades of rubber that will be mixed with additives. “There is also rubber processing chemicals at work,” says Ormonde, along with carbon black and silica plus fiber matrix (textile cord) and steel belt fabric.
Separate compounds are used for different parts of a tire. An industrial mixer typically is used to combine different raw materials for each compound into a homogeneous mixture. Then the compounded materials are processed into tire components. In general, a tire consists of tread (which provides traction and cornering grip), belts (which are used to stabilize and strengthen the tread), sidewall to protect the side of the tire from road and curb damage, body ply to provide tire strength and flexibility, and bead to ensure an air-tight fit with the wheel.
A lot has changed since Eduoard Michelin transformed the tire industry with steel radial in 1946. Today, it is common to find safety systems such as tire pressure monitoring system (TPMS), anti-lock braking system (ABS), electronic stability control (ESC) and supplemental restraint systems (SRS) installed in vehicles. Advanced tread designs by Goodyear Tire & Rubber Co. and Groupe Michelin offer stopping abilities on wet surfaces and low rolling resistance. Rolling resistance is the measure of “force at the axle in the direction of travel required to make a loaded tire roll,” according to a report by the National Research Council (NRC). In other words, it can be viewed as the energy needed by the tire's road contact and deformation.
In Europe, tires with lower rolling resistance are called “green tires” and sometimes described as “energy tires.” Fixing such tires to a vehicle can potentially improve mileage performance by roughly 40% and also extend vehicle servicing intervals, according to a study by the Technical University in Munich. Lower rolling resistance means more efficient control over the correlation among tread pattern, tire structure and rubber compounds.
Today, tire makers are working to meet consumer demand for efficient tire performance on all types of road conditions. Goodyear’s Assurance Fuel Max tires offer what are claimed to be enhanced fuel savings and traction in changing weather conditions. Premier A/S with EverGrip technology by Michelin provides tires with wet grip and performance under cold temperatures. Bridgestone’s DriveGuard run-flat touring tires are intended to take a puncture and keep the vehicle moving for up to 50 miles. And Michelin was able to improve wet traction by adding silica.
To improve the pliability of the rubber in cold temperatures engineers added sunflower oil. Green ingredients such as dandelion flower oil and soybean oil are emerging as materials in the tire manufacturing process. For instance, Goodyear has verified that soybean oil blends efficiently with silica and also reduces factory energy consumption. Soybean oil also is appealing as it would reduce the amount of petroleum-based resources required for tire manufacturing.
Perhaps the most significant biopolymer for the tire industry is natural rubber. Today, essentially all of it is harvested from the Brazilian rubber tree (Hevea brasiliensis). There are a number of alternative natural rubber sources under development, says Ormonde. They are guayule (Partheneum argentatum) and Russian dandelion, but these sources are not mass produced like natural rubber. Some tire companies already have these alternative bio-components, but the tires generally would be more expensive. For instance, Yulex is developing bio-polymer and bio-based resins derived from guayule for tire applications.
These alternate sources eventually may have a role to play, but the market is still years away from making use of them, says Hyde. There are also efforts to develop bio-based feedstocks for synthetic rubber production. “I am aware of significant work underway to producers of bio-isoprene and bio-butadiene,” he says. “So it is possible that we will eventually see bio-based versions of the same synthetic rubber that is currently based on traditional petrochemical feedstocks.”
Ormonde says that the use of bio-isoprene to make polyisoprene rubber remains far-fetched, in part due to low oil prices. What’s more, the economics for bio-based processes currently are not competitive with traditional production techniques. Hyde says the market may be more than five years away from seeing any significant volume of bio-based polymers in the tire market.