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Fluctuating supply and prices o f latex rubber and a growing demand for more eco-friendly technologies are antecedent to the development o f a flourishing green tyre sector, says Angelica Buan.
Global demand for both synthetic rubber and natural rubber is set to grow to almost 40 million tonnes by 2020, according to Singapore-headquartered trade organisation International Rubber Study Group. This projection may encounter a few hiccups as 2017 unfolds since, currently, season-related latex rubber shortage, especially from major Asian producers, is tightening rubber supply, the Association of Natural Rubber Producing Countries (ANRPC) cited in its report published in January.
It mentioned that the global supply of natural rubber will be short of demand by 350,000 tonnes during the year. Likewise, synthetic rubber materials are more expensive this year, stated ANRPC, in anticipation of higher feedstock prices, driven by a call from the Organisation of Petroleum Exporting Countries (OPEC) to cut oil output by 1.2 million barrels/day for the first six months of 2017. The non-OPEC countries, led by Russia and Mexico, also pitched in by staving off an additional 558,000 barrels/ day in oil production.
Apart from the volatile prices, sustainability of tyres is becoming relevant at this time that pollution, climate change and waste management are critical issues.
Turning over a new leaf with green tyres
Green tyre’s eco-friendly edge is having low rolling resistance – the friction between the tyres and the surface. On the contrary, traditional rubber tyres have higher rolling resistance, which require more energy to overcome the friction and so resulting in more pollutants being released.
In the green tyre segment, Netherlandsheadquartered synthetic rubber company, Arlanxeo, has recently introduced new solution styrene butadiene rubbers (SSBR), Buna FX 3234A-2 and Buna FX 5000, that feature first and second generation functionalisation technologies, respectively.
Buna FX 3234A-2, a high styrene SSBR is designed to interact with silica fillers in order to reduce rolling resistance in passenger tyre treads. The product contains 37.5 phr of treated distillate aromatic extract (TDAE) oil, used as a raw material for tyres; and is designed especially for high performance summer tyres, according to Arlanxeo, a joint venture of German speciality firm Lanxess and state-owned petrochemical company Saudi Aramco.
The other product, Buna FX 5000, a high vinyl SSBR, features Arlanxeo´s second generation functionalisation technology. It is also designed to interact with silica fillers to boost fuel economy. This product contains 7 phr TDAE oil extension, which offers the compounder the chance to optimise rolling resistance through the reduction of filler loadings, Arlanxeo states.
Meanwhile, parent company Lanxess also offers a range of eco-friendly tyre solutions through its additives business unit, Rhein Chemie Additives. The products were showcased at the Tire Technology Expo held in Hannover, Germany, recently.
Rhein Chemie Additives has developed a new range of Rhenodiv range of unfilled single-release inside lubes for cleaner tyre production. First to mention are the Rhenodiv BP-337 and Rhenodiv BP-3091 that enable tyre producers to apply very low quantities of inside lube onto the green tyre. The company furthered that in combination with robotic spraying equipment, this allows for a precise coating procedure to be carried out with the assurance that no area of the tyre outside the inner liner will be contaminated. An additional benefit is that Rhenodiv BP-337 is based on hydrogen-free crosslinking chemistry.
In response to an increasing demand for a process that keeps migrating silicones at bay during the tyre moulding process, particularly if a clean, silicone-free tyre surface is required after vulcanisation, Rhein Chemie Additives offers the Rhenodiv BP-166, a lowfilled, silicone-free product; and Rhenodiv BP-9500, an unfilled, silicone-free product.
Other products presented at the show were Rhenomark tyre marking paints, Rhenoshape tyre curing bladders and Rhenogran aramid fibre masterbatches.
German industrial group and silica/silanes producer, Evonik, also presented green tyre solutions with its Ultrasil technology at the German show. It demonstrated that in comparison to conventional tyres made of emulsion-styrene butadiene rubber (ESBR) grade solely filled with carbon black, Evonik said that green tyres with SSBR grades and silica/ silane technology have proven to have significantly lower rolling resistance, resulting in a reduction in fuel consumption by 5% and thus lower CO2 emissions. Additionally, they also have better grip – particularly in wet conditions – while offering comparable durability.
It is because silica serves as active filler in the treads and ensures wear resistance in the tyre, but is actually incompatible with SSBR rubber grades, according to Evonik.
On a larger scale, the green tyres with silica/ silane and SSBR treads are also examined by Evonik in terms of their environmental impact. This is done using a comprehensive Life Cycle Assessment (LCA), which covers production of raw material to end-oflife aspects of the tyre.
Evonik explained that the study analysed impact categories such as the global warming potential, the photochemical ozone creation potential, and the primary energy demands. The functional unit was defined as the use of silica/silane and SSBR in treads of passenger car tyres over a driving distance of 150,000 km; additionally, a sensitivity analysis was conducted with gasoline consumption, fuel savings, and lifetime as parameters.
The study finds that silica/silane technology in green tyres is able to significantly reduce emissions and environmental impacts in the basic scenario in any analysed impact category considered relevant. Consequently, the global warming potential can be reduced by 4.9% in total over the whole life cycle; by replacing carbon black and ESBR with silica/ silane and SSBR, emissions of up to 1.4 tonnes of CO2 equivalents per 150,000 km driving distance are avoidable.
Moreover, the study shows that the use phase has a key impact on the overall lifecycle in all impact categories. Evonik claims that green tyres with silica/silane components, manifesting a significant reduction in fuel consumption, thus, this technology has the potential in reducing emissions in general.
Biobased tyres making a foray
Representing a significant share in the global tyre market poised to reach 2.5 billion units by 2022, forecast by Global Industry Analysts (GIA), green tyres are also those that use elastomers obtained from renewable sources, biomass crops and agricultural residues. Recyclable, green tyres also unburden the environment from landfilled scrap tyres that are not recycled.
Thus, a sustainable option is on the table for tyre makers in the form of biobased rubber. The biobased alternatives to latex rubber making a foray into green tyres, forecast by Smithers Rapra in its report The Future of Green Tires to 2017, are valued at US$70.6 billion by 2017 and growing at a CAGR of 9.5% from 2012.
Rooting for nature-based materials, researchers at the University of Minnesota (UM) have invented a new technology to produce isoprene, a key ingredient in car tyres, from trees, grass and corn. Biomass is converted in liquid phase reactors, and the car tyres produced from the biomass would be identical to existing car tyres with the same chemical make-up, colour, shape, and performance, say the researchers.
The study, published in the American Chemical Society’s ACS Catalysis journal, is a breakthrough in how isoprene is produced. Currently, isoprene can be produced by “cracking” or by thermally breaking apart molecules in petroleum that are similar to gasoline. The isoprene is purified and in the final step, reacted with itself into long chains to make a solid polymer that is the major component in car tyres.
The US National Science Foundation-funded research has hatched a new process by which, sugars are derived from biomass including grasses, trees and corn. The three-step process combines biological fermentation of sugars using microbes with conventional catalytic refining that is akin to petroleum refining technology.
The catalyst used in the process, a recent discovery at the UM, is called phosphorous self-pillared pentasil (P-SPP), a phosphorus zeolite which yields a catalytic efficiency as high as 90%, and thus plays a key role in producing renewable isopropene.
The research team, led by Professor Paul Dauenhauer, anticipates that this development on economically biosourced isoprene is an important step to producing car tyres using renewable, readily available resources instead of fossil fuels.
The University, through its Office for Technology Commercialisation, has applied for a patent on the renewable rubber technology and plans to license the technology to companies interested in commercialising the technology.
Food wastes to hit the road
Vegetable peels may also soon be used in tyres. Researchers at the Ohio State University (OSU) have discovered that food waste can partially replace the petroleum-based carbon black filler used in manufacturing tyres. Based on their tests, rubber with the tomato peels and eggshell fillers exceeded the industrial standards for performance. The finding may ultimately open up new applications for rubber.
Lead researcher and Endowed Chair in Biomaterials at OSU, Katrina Cornish, explains that this technology has the potential to make the manufacture of rubber products more sustainable; reduce dependence on oil exports, and keep waste out of landfills.
Eggs are one of the top most consumed food. A major egg consuming country, US, consumes approximately 248 eggs/person/year, according to the American Egg Board’s 2015 projection. Globally, a person may consume 10.3 kg worth of eggs/year by 2030, citing an estimate of Dr Hans-Wilhelm Windhorst, Director of the Science and Information Centre for Sustainable Poultry Production (WING) at the University of Vechta, Germany.
Tomatoes are also, similarly, widely used as eggs. In 2016, the global tomato processing market reached a volume of 34 million tonnes. The US alone accounts for a third of the total global tomatoes processed.
Eggshells, according to Cornish’s team, have porous microstructures that provide larger surface area for contact with the rubber, and thus provide rubber-based materials “unusual properties”. As for the tomato peels, being highly stable at high temperatures, demonstrate the potential to generate material with good performance.
Meanwhile, it is important to note that carbon black is still incorporated in the tyre, but combined with the ground eggshells and tomato peels to maintain the flexibility of the tyre.
Moreover, because there would be lesser carbon black in the filler mix, the rubber may not look black but rather reddish brown or depending on the quantity of eggshell or tomato in the mix. Cornish’s Ohio-based company, EnergyEne, will be developing this patent-pending technology further. EnergyEne is also responsible for developing and commercialising guayule-based rubber products.
Thus, the traditional rubber market may no longer be dependent on natural rubber resources, if the technology development is successful.
(RJA)