The most basic difference between an electric vehicle (EV) and internal combustion engine (ICE) tyre is that the former demands lower rolling resistance, quieter tread patterns and higher load bearing capacity. While there have been innovations within the tyre industry to meet the current demand for EV tyres, at the molecular level, research and development continues to achieve enhanced compound efficiency as tyre mixtures are complex.

As electric vehicles redefine performance benchmarks, tyre technology is undergoing a molecular-level overhaul. While the industry has focused on rolling resistance, noise reduction and load capacity, Japan’s Kuraray is pushing the boundaries deeper into the chemistry of rubber itself. By integrating silane-functionalised liquid rubbers into natural rubber-silica systems, the company aims to resolve longstanding formulation challenges. These innovations not only offer measurable improvements in abrasion resistance and wet grip but also open the door to broader adoption of sustainable materials in EV tyres. Kuraray’s work signals a strategic shift towards more efficient, adaptable and environmentally aligned tyre compounds.

Japan-based chemicals manufacturer Kuraray has dismissed all odds to achieve a more efficient molecular chemistry in tyres with its silane-functionalised liquid rubbers. In an earlier issue, Tyre Trends had reported how the company’s silane-modified rubber marked a major leap in tyre technology as it enhanced polymer interaction within the tyre, especially in natural rubber and silica-based formulations.

Coming to the present, its silane-functionalised liquid rubbers offer the reduction of rolling resistance (RR) and the resulting compound shows excellent balance of low RR, abrasion resistance and wet grip performance.

Speaking to Tyre Trends exclusively on the development, Technical Service Engineer for Quality and Product Development Department, Elastomer Division, Kuraray Co., Naoto Takahashi, divulged, “We propose to incorporate natural rubber (NR) for silica-based PCR treads. NR is preferable for its high strength and from the viewpoint of sustainability. However, the combination of NR and silica has typically been considered unusual as compounds for PCR treads. One of the reasons is that NR and silica have poor interaction, which causes decrease of physical properties.”

“Our silane-functionalised liquid rubbers can react with silica in the mixing stage and with NR in the vulcanisation stage. Using this technology, NR or silica-based compounds have been proven to have an excellent balance of lower RR and competitive abrasion resistance and wet grip compared to typical styrene-butadiene rubber, butadiene rubber and silica compounds. So we believe it has the potential for EV tyres, which require these properties,” he added.

Furthermore, using silane-functionalised liquid rubber in tyre manufacturing offers several advantages. Firstly, it provides a plasticising effect during the mixing stage, leading to lower torque and electricity consumption.

Secondly, the improved rolling resistance itself contributes to the sustainability goals by extending the driving range of EVs. Long-range EVs significantly reduce carbon dioxide emissions compared to fossil fuel-powered vehicles. This helps mitigate global warming and other climate changes. In addition, EVs with extended range reduce the burden on charging infrastructure and promote efficient energy use. Less frequent charging means reduced strain on the power grid.

Additionally, the improved performance of NR and silica compounds sheds light on the utilisation of NR, which is a kind of sustainable material. “We believe this technology could expand the potential of NR. If you are considering using more NR in your products, then this type of liquid rubber could be useful,” added Takahashi.

MIXING THE MIXTURE

Typically, it has been said that conventional silane coupling agents have poor reactivity with NR. This is not the case for silane-functionalised liquid rubbers. The liquid rubbers react with silica at the mixing stage by hydrolysis and condensation, in the same manner as silane coupling agents. As a result, the silica would be surrounded by hydrophobic liquid rubber chains. This helps silica to disperse well in the rubber matrix.

In the subsequent stage of vulcanisation, the reaction of liquid rubber chains and NR occurs. This forms bonds between two types of rubbers, effectively resulting in reinforcement of silica-NR interaction.

“We believe that these mechanisms contribute to maximising the potential of NR and silica combination,” said Takahashi.

The molecular weight of rubber is another key factor in determining the characteristics of liquid rubbers, alongside the glass transition temperature and monomer components.

Explaining how the molecular weight range of Kuraray’s liquid rubbers affect its compatibility and performance in tyre applications, the executive said, “Our liquid rubbers’ molecular weight range is strategically positioned between typical plasticisers and solid rubbers, ensuring an optimal balance of enhanced processing and physical properties.”

“Each grade’s molecular weight is precisely controlled and tailored to specific purposes and applications. Generally, liquid rubbers with lower molecular weights offer superior compatibility with other ingredients, while those with higher molecular weights provide better physical properties. Interestingly, the viscosity of liquid rubber alone does not determine the processability of compounds. We are glad to support you in selecting the ideal grade of liquid rubber to achieve your objectives,” he added.

He also noted that liquid rubbers have a low tendency to bleed out as a plasticiser because of their higher molecular weight and ability to be vulcanised. The low migration property directly affects the life span of the tyres.

Additionally, the improved abrasion resistance compared to traditional plasticisers also offers the long-term liability of tyres. “Wear particle is one of the biggest issues in today’s tyre industry because it has been recognised that it has a severe impact on the environment. The new regulation to handle this matter has been under discussion for a long time. Our silane-functionalised liquid rubbers would offer the solution to these challenges,” noted Takahashi.

COMPETITIVE EDGE

One of the characteristics of the material is its narrow molecular weight distribution. This provides the benefit of suppressing reduced physical properties due to the low molecular weight fraction. Another is that it has functional groups grafted onto the polymer chain. These functional groups seem to have different reactivity compared to other types of modification.

These features have a positive effect on the storage stability and other performances as tyres. The company highlighted that it has already found that the material would not deteriorate so much for 1-2 years in a bulk container under air.

Besides, the silane-functionalised liquid rubber technology is applicable to various types of tyres including winter and all-season tyres, and high-performance tyres. It is particularly beneficial in improving the dispersion of silica fillers, reducing compound viscosity and enhancing overall tyre performance. This technology helps achieve a balance between grip, low RR and abrasion resistance, making it suitable for a wide range of tyre applications.

Considering the characteristics of the material, another application of this type of material is TBR. Most TBR tyres use NR and carbon black (CB) compounds with less or no oils. However, using silica in place of CB in TBRs is getting more and more attention to achieve the high level of rolling resistance and wet grip performance. Here emerges the problem of NR and silica combination. As mentioned above, the silane-functionalised liquid rubbers would act as the effective additive for these kinds of compounds.

Commenting on the role of the liquid rubbers in enhancing wet or ice grip performance on winter tyres, Takahashi explained, “We have two types of silane-functionalised liquid polybutadiene with relatively higher glass transition temperature (Tg) and lower Tg. Initially,

we only commercialised the former one. However, in response to customer demand, we have developed another grade with lower Tg and are now fully equipped to mass-produce.”

“Liquid rubbers with lower Tg provide flexibility to the compounds even at low temperatures, which is particularly beneficial for the ice-grip performance of winter tyres. This flexibility ensures that the rubber remains pliable and maintains good contact with icy surfaces, enhancing traction and safety. Since the compound Tg is also highly affected by other components such as solid rubbers, plasticisers and resins, we think that our product lineup with different Tg offers freedom of choice for users’ compound formulation,” he added.

MEETING DEMANDS

The company continuously spoke with tyre manufacturers during the development of its liquid rubber. “We have instruments in our laboratory for measuring not only compound properties but also tyre performances such as wet grip and abrasion resistance. This allows us to have close and detailed technical communication with our customers,” said Takahashi.

He added, “The wet grip performance is usually expressed by the value of tanδ at 0 deg.C as an index from the viscoelasticity measurement. But the actual compound’s grip performance often shows a different result from the viscoelasticity. We have equipment to measure the friction coefficient of compounds on wet and icy surfaces, allowing us to minimise the discrepancy between viscoelasticity and grip performance.”

Alluding to how the use of silane-functionalised liquid rubber in EV tyres aligns with current trends and future directions in tyre technology, he said, “We recognise the growing trend towards sustainability as well as the importance of reducing rolling resistance and wear particles. Here, we recommend using NR more to address these issues. While the combination of NR and silica may not be the conventional choice for PCR tread compounds, we believe that our innovative approach demonstrates the potential of this formulation. The use of silane-functionalised liquid rubber offers the excellent dispersion and reinforcement of NR and silica compounds, paving the way for the solution to address future challenges in tyre technology.”

Takahashi indicated that the silane-functionalised liquid rubber can play a role in reducing the carbon footprint of tyre production. The key driver, he explained, is a measurable drop in rolling resistance, which translates into lower fuel consumption for internal combustion vehicles and reduced electricity use in EVs.

The firm also highlighted its broader sustainability efforts, noting that its liquid rubber plant is ISCC Plus-certified. From this year, Kuraray has started producing sustainable materials under a mass-balance approach – an initiative that includes its latest silane-functionalised grades, though the product range is still expanding.

On managing cost-performance trade-offs, he acknowledged that liquid rubber typically commands a higher price than traditional plasticisers. However, the benefits tend to supplement the cost.

The company pointed to challenges like dispersing high-surface-area silica in tread compounds – an area where its liquid rubber grades can provide a processing advantage. It also emphasised the potential of NR and silica combinations, made feasible with its silane-modified products, as an example of how formulation innovation can justify the premium.

Kuraray’s silane-functionalised liquid rubber represents a critical inflection point for tyre formulation – technically and environmentally. By enabling stable silica dispersion in natural rubber and forming durable crosslinks during vulcanisation, it addresses both performance and sustainability imperatives.

While the cost remains a consideration compared to traditional plasticisers, the material’s added value, such as reduced energy use, lower rolling resistance and extended tyre life, could redefine return on investments calculations for manufacturers. Its compatibility with evolving regulations on wear particles and carbon footprint reduction positions it not just as an additive but as a strategic material. The challenge ahead lies in scaling adoption without compromising economic efficiency.

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The Government of Kerala has approved the twelfth phase of the Rubber Production Incentive Scheme, extending support to natural rubber growers through a guaranteed price mechanism.

The scheme is designed to ensure a price of INR 250 per kilogram for RSS 4 grade sheet rubber. Growers who are not yet enrolled may register for the programme until 23 October 2026, according to an official statement issued on 6 August in Kottayam.

Applicants seeking new registration must submit an Aadhaar card, bank passbook copy, current year land tax receipt and a photograph to their respective Rubber Producers’ Societies. Existing participants are required to renew their registration by providing land tax receipts for the 2026–27 period.

The release added that sale invoices or purchase bills submitted under the scheme must originate from licensed dealers who comply with statutory return requirements. Further details are available through the nearest Rubber Board office.

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The Rubber Board of India has launched a series of educational videos as part of the iSPEED (INROAD Skilling and Production Efficiency Enhancement Drive) programme, an INR 1.50-billion initiative aimed at enhancing skill development, quality improvement and infrastructure building within the natural rubber sector. This launch comes as the plantation activities under the larger Project INROAD (Indian Natural Rubber Operations for Assisted Development) in Northeast India approach completion, shifting focus towards productivity and quality enhancement through modern training and facilities.

The newly released video series targets nearly 300,000 rubber growers in the region, covering five essential processing areas: Rubber Tapping, Rain Guarding, Grading, Rubber Sheet Making and Scientific Smokehouses. To ensure broad accessibility, the modules have been produced in Assamese, Bengali, Hindi and Malayalam, enabling effective communication with diverse stakeholders across the natural rubber ecosystem.

The official release of the videos was conducted by Executive Director M Vasanthagesan, alongside Rubber Production Commissioner Dr Siju T Nair, other senior Board officials and representatives from the Indian tyre industry. Developed over the past year with technical assistance from the Rubber Board and the Rubber Research Institute of India, the educational content combines animation with real-life field demonstrations to simplify complex scientific practices for easy adoption.

Project INROAD represents a unique collaboration between the Indian tyre industry and the Rubber Board, with support from Apollo Tyres, CEAT, JK Tyre and MRF. Over the last five years, this partnership has facilitated new rubber plantations across approximately 180,000 hectares in 113 districts of Northeast India, establishing it as the country’s largest plantation development programme of its kind.

Mohan Kurian, Chairman, INROAD Project, said, "Skill development and adoption of scientific practices are essential for improving both productivity and quality in the natural rubber sector. These multilingual videos will serve as an effective training resource for growers and complement the Rubber Board's ongoing extension efforts across the country.”

Sanjiv Saxena, Convener, ATMA Supply Chain & Resources (SCR) Group, said, "The objective of the participating member companies under INROAD is to ensure that rubber growers benefit the most from a stronger natural rubber value chain. By improving productivity and quality, we aim to help farmers realise better returns while strengthening the sustainability of the entire ecosystem."

Muraligopal, who played a key role in coordinating the development of the videos, said, "These videos are the result of close collaboration with the Rubber Board, RRII and field teams across the Northeast. Their guidance and support helped us develop practical, farmer-friendly training modules based on scientific best practices."

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Zeon Corporation has finalised the construction of a new bench-scale facility at its Tokuyama Plant in Shunan City, Yamaguchi Prefecture, dedicated to advancing the efficient production of butadiene from sustainable ethanol sources. The project, which broke ground in July 2025, represents a strategic move to establish a naphtha-independent raw material supply chain, thereby bolstering both corporate sustainability and the broader transition towards a carbon-neutral society. The facility is slated to commence full-scale operations in January 2027, with the ultimate goal of achieving commercial viability by 2034.

A commemorative ceremony took place at the plant site on 31 July 2026, drawing a total of 46 attendees. The gathering included official representatives from Japan’s Ministry of Economy, Trade and Industry (METI), the New Energy and Industrial Technology Development Organization (NEDO) and local governmental bodies from Yamaguchi Prefecture and Shunan City. Also present were delegates from the Yokohama Rubber Company, the construction contractor and various affiliated firms, alongside Zeon’s leadership, including Akira Honma, the Corporate Officer and Tokuyama Plant Manager.

This initiative forms one half of a dual-themed research and development programme undertaken in partnership with Yokohama Rubber, under the auspices of NEDO’s Green Innovation Fund. The collaborative effort is focused on the social implementation of technologies for synthesising both butadiene and isoprene from renewable biological materials by the 2030s. As part of this process, Zeon is set to produce a prototype polybutadiene rubber using the output from the new bench-scale facility, while Yokohama Rubber will subsequently manufacture test tyres from this material and conduct performance evaluations on test tracks.

Both companies have outlined a clear roadmap, intending to finalise the core technology for societal deployment by 2030 through the operation of a larger pilot plant, with full-scale commercialisation targeted for 2034. The bench-scale facility is a critical precursor in this phased approach, providing essential data for the scale-up process.

The broader project encompasses two selected NEDO themes, both subsidised through the Green Innovation Fund. The first involves the highly efficient synthesis of butadiene from ethanol, with technical cooperation from the National Institute of Advanced Industrial Science and Technology. The second focuses on biotechnological pathways to directly produce butadiene and isoprene from plant-based materials, involving partnerships with the Institute of Science Tokyo and RIKEN. Both tracks aim to supplement synthetic rubber feedstocks and support closed-loop recycling, aligning with Japan’s 2050 net-zero emissions goal by fostering long-term industrial innovation.

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The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly Natural Rubber Statistical Report for June 2026, a month defined by price resilience amid conflicting market forces. The provisional reopening of the Strait of Hormuz triggered a sharp 20.29 percent drop in Brent crude oil prices to USD 85.40 per barrel. However, this bearish signal was counterbalanced by persistent supply constraints from El Niño-related weather disruptions across major producing regions.

Physical rubber prices posted broad-based gains across most grades. SMR-20 rose 1.39 percent to USD 2.32 per kilogramme, while STR-20 gained 2.61 percent to USD 2.55 per kilogramme. RSS-3 and RSS-4 advanced 4.98 percent and 5.88 percent to USD 3.09 and USD 2.84 per kilogramme, respectively, though latex eased 1.44 percent to USD 1.94 per kilogramme. On the trade front, China's imports surged 7.14 percent month-on-month, while India and Viet Nam declined. Export growth was recorded for Cambodia, Viet Nam and Indonesia, though Thai shipments contracted.

Global production for 2026 is projected at 15.310 million tonnes, up 2.3 percent from 2025, driven by gains in Thailand, China, India and Malaysia. However, June output fell 3.7 percent year-on-year to 1.207 million tonnes due to seasonal wintering and El Niño-related weather disruptions. Malaysia, Indonesia and Cambodia have introduced new incentive and governance measures to strengthen their sectors. Global consumption is forecast to grow 0.7 percent to 15.411 million tonnes in 2026, with June consumption rising 3.3 percent to 1.300 million tonnes, led by China and India amid steady tyre and EV-related demand.

Currency markets saw the Malaysian ringgit trade between RM3.96 and RM4.08 against the US dollar, while the Thai baht ranged from 32.56 to 33.24. In futures trading, the SHFE September 2026 contract averaged 17,580.68 CNY per tonne, down 0.45 percent month-on-month, while the SGX September contract averaged USD 2.24 per kilogramme, up 1.75 percent, with both reflecting tightening supply and firm downstream demand.

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