November/December 2008
As manufacturers try to improve tires' safety and performance, tire processors worry about how new materials and designs will affect recyclability and end-use markets.
By Chelan David
Tire manufacturers are in a constant quest to build a better tire: one that's lighter, stronger, and more durable. At the same time, they want a tire that is less expensive to produce, provides a more comfortable ride, delivers better traction, and minimizes its impact on the environment. To achieve that multitude of goals, they experiment with a variety of designs and materials, from the familiar—rubber, steel, and various kinds of fiber—to the exotic—polyurethane spokes, for one.
Tire processors are on a constant quest, too. They want to take a tire, process it, and find a market for each of its components. They've made solid progress toward that goal over the past 15 years. According to a 2006 report by the Rubber Manufacturers Association (Washington, D.C.), only 11 percent of scrap tires (about 25 million tires) were recycled or reused in 1990; by 2005 that proportion had increased to nearly 87 percent, or 259 million tires. "The demand for tire-derived products is at an all-time high," says Michael Blumenthal, RMA's vice president.
Tire recyclers worry, however, about how new tire designs and materials will affect their processing equipment and the consumer base in this still-fledgling industry. "I believe that any processor has the same concerns about new [tire] technologies as I do," says Jerry Swensen, president of Auburndale Recycling Center, a tire processor in Auburndale, Wis. "It's not knowing what's coming down the road next and how it will affect my operation."
Today's Material Concerns
Tire designers have two goals: increasing safety and increasing performance. Government standards and consumer demand play a large role in determining how well tires meet those goals and whether they make it into the marketplace. Various regulatory agencies test tires for speed, endurance, strength, and bead-seating—how well the tire adheres to the wheel. They also rate tires on traction, tread wear, and temperature. Customers want their tires to provide better fuel economy, a smoother ride, greater traction, and slower tread wear—all for a lower cost.
One new material manufacturers are using in tires to achieve those goals is silica. When used in place of carbon black (a component of tire rubber), silica can decrease a tire's rolling resistance—how much friction is created between the tire and the road surface. In general, the lower the rolling resistance, the better fuel economy the tire provides. But silica does not have the same chemical properties as carbon black, and tire processors have determined that ground rubber made from silica-containing tires has a greater ash content. The silica "changes the properties of the finished product, especially when producing fine-grind crumb," Swensen says. Some end-use customers have extremely tight specifications for the crumb they use in their products, he says, and adding silica—or other compounds and fillers—can affect the ability of the crumb to meet those specs.
The end result is bad news for both the processor and the consumer of the tire-derived product, Swensen says. If the proportion "of silica or other compounds gets too far out of the acceptable range, customers may discontinue using the crumb we produce." They might switch to other types of rubber, which "can add considerable cost to their product," he says, and such concerns can reduce the demand for recycled crumb.
RMA is working with ASTM International (West Conshohocken, Pa.), the international standards organization, to change the specifications for ground rubber to account for the introduction of silica into tires, Blumenthal says. "When a laboratory runs an assay on ground rubber, they are going to get certain readings. Because of the use of silica instead of more traditional materials, we have to change the ASTM specification for ground rubber," he says.
Silica does not cause problems for the equipment tire recyclers use to process tires, says Mike Hinsey, international vice president of Granutech-Saturn Systems Corp. (Grand Prairie, Texas), a manufacturer of such equipment. "The silica does not separate from the other [rubber] components, so there is not a need to have specific separation machinery for it." That said, another new tire design—the run-flat tire—has created processing problems. "Run-flat tires can contaminate finished products," Swensen says, "and if not handled properly, they can increase wear on the equipment or cause blinding in screens, which can dramatically affect the processing operation." Keeping a clean, well-maintained system with sharp blades can help processors avoid damage to equipment, Blumenthal says. "Making sure you have the right blades [and that] they are sharpened, maintained, and rotated on a regular basis is critical," he says.
The Tires of Tomorrow
With the design of new tires constantly in flux, the great unknown is how the tire recycling industry will fare with the tires of tomorrow. With new regulations, shifting customer preferences, and changing specifications from automakers, it's hard to predict what type of tires will be prevalent in the next five to 10 years, but some trends are becoming clear.
Right now, tire manufacturers face significant economic pressures: Costs are rising for raw materials such as oil and natural rubber. Even though sales numbers have gone up for many tire companies, they can't raise prices fast enough to offset increased costs, thus they're losing money. "Right now, the focus for tire manufacturers is to find ways to reduce costs of manufacturing [and] find new materials that are less expensive and will still provide the same level of safety and performance," Blumenthal says. As long as raw material prices continue to go up, that trend will continue.
High oil prices also affect consumers' choice of vehicle. Just four years ago, Blumenthal says, U.S. consumers purchased more SUVs and light trucks than passenger cars. Now the pendulum has swung back, as major auto manufacturers try to meet demand for smaller vehicles that get better gas mileage. If this trend continues, sales of passenger tires should surpass sales of SUV and light truck tires in a few years. Of course, owners of even the smallest cars would like to improve their gas mileage, making better rolling resistance a continuing concern of tire purchasers.
Gary Champlin, general manager of Champlin Tire Recycling (Concordia, Kan.), predicts an increase in performance tire design, more run-flat tires, and even tires that don't need to be inflated. One prototype tested by Michelin (Greenville, S.C.), dubbed the "tweel," consists of a band of tread surrounding a tire made of flexible polyurethane spokes.
Long before a new design that radical becomes prevalent, tires of the future will change in terms of "the components that make up the tire itself," Swensen says. "New compounds for the rubber are being explored on a daily basis, along with new steel and fibers that provide the stability and durability that is required." In other words, the tires will look substantially the same—but the materials they contain might be substantially different.
Such product changes could have wide-ranging effects on tire recycling, processors say. The biggest concern, Swensen says, is that the new products will "interrupt otherwise consistent and steady markets" as recyclers adjust to processing them and consumers adjust to using them. That slowdown could create "backlogs of materials that can create environmental and safety risks to our business and the general public," he says.
Tire piles are more than just an eyesore. They provide a sanctuary for vermin, and the water than can collect in them is a breeding ground for mosquitoes that may harbor diseases. Also, poorly managed stockpiles of tires build up heat that can erupt into fire, potentially burning for months and creating substantial air pollution. Landfills don't want tires, either—they're bulky and they decompose slowly.
Even worse, Swensen says, is if crumb rubber containing some new material makes its way into a finished product that turns out defective or otherwise unusable because of that material. The consumer of the processed rubber can't use it, and the processor faces huge costs associated with removal, disposal, and replacement of the undesirable material.
New materials could have some beneficial potential, too, Hinsey notes. An increase in the proportion of nonrubber components and a decrease in the amount of recoverable rubber could lead to new markets. Processors already are increasingly finding markets for the fluff—the fibers and other nonrubber materials removed from tires during processing.
As new materials enter the scrap tire stream, processors and equipment suppliers will have to adapt. "Each nonrubber byproduct has its own challenges in processing to an end market," Champlin says. The ability to separate and process any new material—Hinsey gives the example of the heavy filament fiber present in some truck tires today—will be essential to finding end uses for it. "First, we will need to source separate," says Charles Astafan, general manager of Columbus-McKinnon Corp.'s facility in Sarasota, Fla., "then we will need to develop alternative processing systems and develop alternative markets for the end products produced." Neither he nor Hinsey thinks new tire designs will require dramatic changes in processing equipment. Astafan does worry, however, that new components might reduce efficiencies, as they could be more difficult to separate and recycle.
Communication and Cooperation
The primary aim of a tire manufacturer is to construct a safer, more durable tire; the primary aim of a tire processor is to deconstruct the same product as efficiently as possible and find markets for each commodity. That said, both ends of the tire life cycle want to find safe, environmentally friendly uses for end-of-life tires.
Over the past year or so, representatives of ReMA and RMA have discussed the concerns of processors and the issues the tire recycling industry faces. Jonathan Levy, ReMA's director of state and local programs, stresses the importance of keeping open lines of communication between the two industries. By engaging in continual dialogue, he says, RMA learns about tire processors' challenges, and ReMA members can gather information about how they will need to adapt to new tire designs. "We want to give them an understanding of our processes and some of the challenges we face," Levy says. "We need to continue to talk with them and have them talk with us."
Cooperation benefits all, Hinsey says. "The manufacturers want to minimize producer-responsibility obligations and expenses related to handling scrap tires, and the simplest way to achieve that is to be open and cooperative with processors," he says. On the recyclers' end, "processing scrap tires is a tough business, and any effort to make the business easier or more rewarding is welcomed. The processors are not looking for a free ride from anyone," he says, they just want to "know what is expected tomorrow." The two groups might even find common ground, such as the need to reassure the public about the safety of crumb rubber in athletic field applications.
Processors complain that tire manufacturers fail to provide them with information about new tire composition in a timely manner. Giving recyclers "a certain amount of time to adjust to these new designs before they arrive at our door will give us an opportunity to explore new equipment, processes, and markets without interrupting the flow," Swensen says. "Without being given that time to explore and adjust, when a totally new design does show up, we stand there, scratch our heads, and say, 'Now what?'" Blumenthal says RMA tracks new tire features and posts the information on its Web site. It's simply not possible to provide processors with information about new tire designs any earlier, he adds—even he doesn't know what's coming down the pipeline until he reads about it in trade publications. The manufacturers "consider it proprietary information," he says.
Regardless of when processors learn about changes in tire design, they will have to adapt to accommodate them. Change is inevitable, Hinsey says, "but with cooperation from all parties—processors, tire suppliers, and machinery producers—I don't see a major design issue that can't be overcome on the processing side."
As Swensen puts it, "I think it's safe to say that, with an industry this young [that's] still growing dramatically, you would be hard-pressed to find a processor who will say, 'My plant is finished, no more changes.' We are constantly changing to adapt to new demands, and we always will be. That's what makes what we do so entertaining." •
Chelan David is a writer based in Seattle.
As manufacturers try to improve tires' safety and performance, tire processors worry about how new materials and designs will affect recyclability and end-use markets.