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 Polymer Industry Cluster, in partnership with The University of Akron (UA), has announced the selected location for a new innovation pilot facility dedicated to provide crucial resource for innovators by offering the specialised space and equipment needed to transition new materials from research to market.

A significant advancement for Northeast Ohio's polymer industry, the new scale-up facility will be built on the UA campus next to the existing National Polymer Innovation Center building. This proximity is designed to foster a powerful collaborative environment, giving users direct access to the centre’s advanced resources and expertise. Its location at the heart of the region's polymer corridor will provide a centralised hub for businesses and researchers across the area.

A primary goal of the initiative is to fill a recognised void in the product development cycle. The facility will offer turnkey operational space for both startups and established companies to conduct initial production runs and refine their manufacturing processes before committing to full-scale commercial operations. This support is vital for de-risking innovation and accelerating the launch of new advanced polymer products.

Funding was secured through a USD 31.25 million award from the State of Ohio's Department of Development, granted under the Greater Akron Polymer Innovation Hub programme. This state investment is further strengthened by an additional USD 10.4 million in matching contributions from local partners. The construction timeline is set to begin in the second quarter of 2026, following the vacating of the current Lincoln Building on the site and pending final state approvals. This project underscores a shared commitment to strengthening Ohio's position as a global leader in polymer science and manufacturing.

Hans Dorfi, Executive Director and Chief Innovation Officer, Polymer Industry Cluster, said, “This project underscores Akron’s position as the hub of polymer innovation. By placing this facility next to NPIC and close by other polymer and engineering labs, we’re ensuring that entrepreneurs, researchers and industry partners have the tools, environment and support needed to transform new ideas into commercial realities.”

UA President R J Nemer said, "The University of Akron is excited to make room for the polymer facility project. As the number one institution in the world for polymer science and plastics engineering, we look forward to working with our Akron area partners to elevate polymer research, expand development and amplify production right here at the UA campus."

Akron Mayor Shammas Malik said, “Locating the Polymer Industry Cluster innovation pilot facility on The University of Akron Campus demonstrates the importance of the University as a force for education and innovation within the pipeline of polymer development from idea to industry. This new addition complements the work of Bounce Innovation Hub, builds a new resource for our industry partners and highlights the City of Akron as the centre of polymer innovation at the state and national level. This new facility will be just a short walk from Akron's Rubber Worker statue in the heart of downtown which illustrates the importance of Akron's rubber past as a foundation for our polymer future.”

Mark Smale, Executive Director – Advanced Polymer Science, Bridgestone Americas and co-chair of the Polymer Industry Cluster, said, “This facility will represent a transformational step for the Polymer Industry Cluster. It will attract start-ups seeking to validate new materials, researchers aiming to commercialise discoveries and established companies looking to innovate without interrupting their current operations.”

Summit County Executive Ilene Shapiro said, “This new facility is not just an investment in physical infrastructure. It’s an investment in the future of our economy. By strengthening our position as the global centre of polymer innovation, we are attracting new jobs and talent and ensuring that groundbreaking research and manufacturing will continue to thrive right here in our region for generations to come.”

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A delegation from the All Kerala Small Scale Tread Rubber Manufacturers' Association (AKTRMA) and the Kerala Small Scale Industries Association (KSSIA) met Kerala Finance Minister K N Balagopal and Secretary for Resources Ajit Patil on 18 September 2025, to address the issue of Goods and Services Tax (GST) on tractor tread rubber used for retreading.

The delegation led by A Nisarudheen, State President of KSSIA and Alias Mathew, General Secretary of AKTRMA highlighted the negative impact of the current GST structure on small and medium-scale retreaders, which are crucial to the rural economy. They emphasised the need for GST rationalisation to ensure fair taxation and the long-term viability of the industry.

The industry bodies stated that both the Finance Minister and the Secretary for Resources were receptive to the concerns and gave assurances that the matter would be given serious consideration. They also promised a follow-up meeting once the process begins.

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Solvay is expanding its global circular economy strategy by converting its Asian production of highly dispersible silica (HDS) to use certified circular raw materials. Beginning in 2026, its plants in Qingdao, China, and Gunsan, South Korea, will transition to using ISCC+ certified waste sand. This major initiative is projected to make over half of the region’s HDS output circular, directly aiding tyre makers in their goal of incorporating over 40 percent sustainable materials by 2030.

This transition provides tyre manufacturers with a cost-effective, high-volume circular Zeosil silica that integrates seamlessly into existing processes without the need for reformulation. The move builds on the successful conversion of Solvay’s Livorno, Italy, facility to using rice husk ash and reflects a coordinated, global shift towards circular sourcing. It also supports the broader sustainability goals of Solvay Silica, including the adoption of low-emission technologies like electric furnaces to minimise the carbon footprint of its products worldwide.

By pioneering circular silica from diverse feedstocks and regions, Solvay is fostering more resilient and sustainable supply chains through innovative partnerships across the entire value chain.

An Nuyttens, President of Solvay’s Silica Business unit, said, “Solvay’s circular silica helps improve fuel efficiency and EV range, offers long-lasting wear benefits, improves safety, while advancing sustainability. This is more than innovation - it’s a reinvention of how we source, produce and collaborate across the value chain.”

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Following the formal approval of its foundational design, Sinopec has announced the construction of a new green, high-end rubber materials facility in Tianjin, China. The project, which was initially revealed in 2023, represents a total investment of CNY 2.452 billion (approximately USD 344.65 million). Its production output will include 100 kilotonne per annum (ktpa) of solution styrene butadiene rubber and an equal volume of nickel-based butadiene rubber.

Operated by Sinopec’s Beijing Yanshan branch, the venture will be funded through a combination of 70 percent bank loans and 30 percent company capital. The initial construction phase, focused on piling work for processing units, storage areas and auxiliary facilities, is valued at CNY 28 million (approximately USD 3.94 million) and scheduled for completion within 31 days.

This new rubber plant is an integral component of the larger Sinopec Nangang high-end materials industrial cluster, which also features a recently completed 1.2 million tonne-per-year ethylene complex. Encompassing a 277,004 sqm site with a built area of 43,522 sqm, the facility is projected to become operational in 2027.

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