Tiremakers are leaving no stone unturned in the re-search for sustainability and savings
The milky sap in a Russian species of dandelion contains raw rubber of the same quality found in Hevea rubber trees. Currently, companies like Continental, Ford, Cooper and Bridgestone are working with researchers to harvest and integrate the ingredient.
Manufacturers are cooking up all kinds of recipes that feature new raw materials intended to reduce tire weight without losing tire performance, improve fuel efficiency by reducing rolling resistance, and lessen product and process carbon footprints through green, sustainable technologies.
“As of 2010, there were approximately one billion vehicles in service around the world,” explains Chuck Yurkovich, vice president of global research and development for Cooper Tire & Rubber Co. “This number is expected to double by 2030 due to increasing global population levels and middle-class growth in countries like China, India and Brazil. As a result, Cooper and other tire companies continue to explore and develop new raw materials to address these issues.”
Not only are consumers demanding green tires because of increased environmental awareness, Yurkovich says other issues are driving the implementation of new materials, as well. Sustenance of a healthy environment demands that CO2 emissions be reduced, as stated in the Kyoto Protocol, which expects that reduction by 2020. Governmental regulation – including that of tire labeling, 2025 CAFE standards of 54.5 mpg and the like – makes new technologies a priority.
Sheer economics indicate that future costs of agriculturally derived materials may be preferable to those of oil-derived products. And potential shortages of traditionally used raw materials like natural rubber and synthetics are becoming an urgent consideration.
So, Yurkovich says, tire companies are increasingly looking into the use of new materials. Among them are:
- Bio-oils from canola, corn and soy;
- Fillers from agricultural products like starch, rice, soybean and corn;
- Domestic sources of natural rubber such as dandelion, guayule and TKS;
- Nano-fibers from biological and synthetic sources;
- Functionalized polymers, both synthetic and from natural rubber;
- Microbially-produced biopolymers;
- Higher surface-area silica (greater than 200 BET or CTAB);
- Higher tensile steel cord configurations to reduce tire weight;
- Lighter-weight reinforcements to replace steel;
- Master-batch technologies that will process these improved materials, which can’t always mix easily with conventional technologies.
“We are seeing a large transition in the tire business and its products as exciting new materials and technologies are developed,” Yurkovich says. “It’s definitely a work in progress, but we anticipate the development of new materials will continue and even accelerate in the next five to 10 years.”
Planting an Idea
Given the nature of these new raw materials, everyone from Ohio farmers to Russian and German scientists are now in the tire business.
Ever since Russians discovered in the 1920s the potential for harvesting rubber from dandelions, that pursuit, abandoned after World War II, has been an industry pipe dream. Because natural rubber – which provides greater resistance (more durable) than synthetic rubber – is derived largely from small rubber tree farms in Indonesia, Thailand and Malaysia, it’s a limited commodity.
But when scientists in Germany later discovered that the milky sap in a Russian species of dandelion contains raw rubber of the same quality found in Hevea rubber trees, manufacturers took note.
Today, companies like Continental, Ford, Cooper and Bridgestone are working in conjunction with researchers at facilities like the Ohio Agricultural Research and Development Center to harvest and integrate the ingredient. These researchers, after all, say that one acre of Russian dandelions could eventually produce as many as 250 truck tires, providing a higher yield than other alternative rubber-producing plants. With natural rubber prices rising from 50 cents a pound in 2003 to $3 a pound in 2011, it’s an alternative worthy of serious consideration.
“We know that there are more than 1,200 types of plants from which natural rubber could, in theory, be harvested,” says Hiroshi Mouri, president of Bridgestone Americas Center for Research and Technology, in a press release. “But finding one that could practically produce the quality and amount of rubber needed to meet the demands of today’s tire market is a challenge…We’re excited about this potentially game-changing discovery with the Russian dandelion.”
Continental, meanwhile, has been following research into dandelion rubber since 2007, and is presently working in a research consortium to explore its capabilities. “The Russian variant provides a higher yield of natural rubber than the common dandelion,” says Dr. Boris Mergell, Continental’s vice president for material, process development and industrialization for tires, in a press release. “It could significantly reduce the pressure on conventional rubber supplies.”
Many manufacturers considering the use of dandelion rubber also are investigating the implementation of guayule as a natural rubber substitute. The shrub, native to the southwestern U.S. and northern Mexico, is similar to the Russian dandelion in that it, too, has qualities identical to those of natural Hevea rubber.
Goodyear, Firestone and the now-defunct Uniroyal Tire Co. in the past experimented with the raw material, some even planting acres of the shrubs in Texas and Arizona. Last spring, Bridgestone announced plans for extensive research into developing guayule as a commercially viable, renewable source of high-quality natural rubber.
“This is such an exciting and innovative project,” said Bill Niaura, director of new business development for Bridgestone Americas, in a press release at the time. “It will not only help our companies meet the strong, anticipated growth in demand for natural rubber, but also constitutes a potential breakthrough for the rubber industry. This project demonstrates our commitment to environmental stewardship and sustainability through its potential to develop a renewable resource for natural rubber that can be grown, harvested and processed closer to market.”
“As the global supply for natural rubber continues to decline, it’s becoming increasingly vital to identify a sustainable, high-quality alternative source of natural rubber,” agrees Cooper’s Yurkovich. “The biopolymers (extracted) from the guayule plant are used as a replacement for traditional tropical or petroleum-based rubber. Production of this bio-based material is ecologically responsible and carbon neutral, and the material itself is valued for its physical performance, including increased elasticity, functionality, reliability and strength.
“If successful, (Cooper’s research into guayule in concert with Yulex Corp.) will create a new agricultural polymer with broad-based tire industry applications,” Yurkovich adds. “It will convert desert wasteland into viable farmland for associated crops, and it will create jobs for American workers.”
A Well-Oiled Plan
Also rising from the land are soybeans, corn and canola – all of which provide bio-oils that can replace petroleum oils in tires. Manufacturers including Goodyear and Bridgestone already have started implementing their use. And, in some cases, that usage creates a symbiotic relationship.
“Our goal is to have soy oil as a component in all of our agricultural tires by the end of 2013,” says Tom Rodgers, director of agricultural tire sales and marketing at Bridgestone, in a press release. “Any opportunity to enhance the value of the commodities our customers produce is a win for the industry. It’s exciting to have the opportunity to be a customer of our customers, and we’re confident that the innovation of using soy oil in our tires is a positive for the global food market.”
Fillers also are being derived from naturally grown products such as starch and rice, in addition to soy and corn, improving sustainability as they replace carbon black produced from petroleum oil. They also have the potential, Yurkovich says, to improve tire rolling resistance and weight.
Meanwhile, traction, tread life and fuel efficiency due to decreased rolling resistance reportedly all are improved with the use of orange oil in tires. Yokohama is among the manufacturers already using the ingredient. Similarly, Nokian is using a silica-canola oil compound to lower rolling resistance; Michelin is using sunflower oil to improve traction; and Sumitomo is incorporating vegetable oil, reinforced with fibers made from plant cellulose.
But the implementation of these farmed ingredients isn’t entirely without potential problems. “The use of these new materials has the potential to displace food-crop production, along with creating water shortages, if not properly managed,” Yurkovich explains. “In addition, many of these technologies don’t, at present, compete economically with oil-derived materials – nor yet offer acceptable performance.”
To that end, some companies are developing bio-based alternatives to petroleum-derived isoprene for the production of synthetic rubber and other elastomers. Goodyear, for example, is working with DuPont Industrial Biosciences to develop a product called BioIsoprene, and unveiled a prototype tire last year that boasted its inclusion. Created from what Goodyear simply calls renewable raw materials, the product also is intended for use in surgical gloves, golf balls and adhesives.
Other companies are focusing on different ways to create sustainable replacements for synthetic polymers and associated rubber compounds. Lehigh Technologies, a provider of sustainable rubber materials to the tire industry, has partnered with HERA Holding, a Spanish environmental group, to offer micronized rubber powder made from discarded tires and other post-industrial rubber to its customers, which include five of the top 10 global tire manufacturers.
The company calls the powder the most sustainable tire material on the market, reducing the need for virgin or synthetic petroleum-derived materials. Lehigh claims it’s already used in more than 140 million tires worldwide.
Rolling With the Changes
As these raw materials enter the marketplace, others obviously will be displaced. Among them are carbon black, replaced by silica and other fillers to improve rolling resistance and traction while reducing petroleum use; aromatic oils, replaced by clean petroleum oils and bio-oils for improvements in health and environment; and emulsion SBR polymers, replaced by solution SBR, functionalized SBR and functionalized natural rubber, for better tire performance.
“The use of all of these materials is currently on the decline, and will continue to be as long as the current drivers are in place,” Yurkovich says of his original list of pivotal circumstances. “We believe ‘decrease and decline’ is more accurate than ‘disappear’ for carbon black and emulsion SBR, though aromatic oil may disappear totally.”
As for the rate of increase for the use of new materials, Yurkovich says those same drivers will determine its speed. “We anticipate this will take place gradually over time, with a few new materials added every four to five years,” he says. “Though large-supply quantities of domestic natural rubber are many years out, small quantities may be used in tire industry products within the next five years.”
So, what does all of this mean to the tire dealer and, just as importantly, to the customer?
“Tire dealers and consumers will see lighter-weight tires with improved performance and overall customer value,” Yurkovich says. “But prices will increase somewhat due to the new materials used to obtain this performance level.”
Given the benefits to the customer, the dealer, the industry and the planet, that may be a small price to pay.
|But Can We Replace This Raw Material: Air?
Airless tires have the potential to improve safety or productivity in applications where tire air loss is a major concern. This has the most opportunity to benefit the customer if commercialized for use in heavy industrial and commercial tires (agricultural, mining, logging), off-road tires (4X4 vehicles, ATVs), motorcycles, military tires (Humvees), and certain public transportation tires (airplanes, buses, taxis).
Airless tires also have the potential to improve fuel efficiency (air loss impact on rolling resistance). Implementation of other technologies, such as TPMS inflation systems, have the potential to dramatically reduce these benefits.One major concern: The modern pneumatic tire has co-evolved with the automobile for nearly a hundred years. It’s extremely challenging to duplicate the ride and handling characteristics, traction and treadwear performance, and durability of a pneumatic tire with any of the proposed airless concepts.The emergence of entirely new mobile platforms, such as the Segway and ultra-light personal transportation systems, may open up the design envelope for airless tire concepts for niche applications.
Airless tires will typically weigh more than pneumatic tires. More material – polymeric web – is needed to carry the same load as today’s pneumatic tire. Since air weighs less than re-enforcing materials, the airless tire will inherently weigh more than a pneumatic tire. Other potential issues are associated with reducing tire noise and maintaining or improving durability.Airless tires will most likely come into production for specific niche-tire applications if the primary challenges can be overcome within the next five to seven years. We don’t anticipate broad-based applications in the near term.Source: Chuck Yurkovich, vice president of global research and development, Cooper Tire & Rubber Co.