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.

Ecolomondo Corporation, a Canadian leader in sustainable scrap tyre recycling, has achieved a significant milestone as its primary offtake client has officially approved the quality of the recovered carbon black (rCB) produced at its Hawkesbury Thermal Decomposition Process (TDP) facility. This approval follows the successful commissioning of new milling equipment and an rCB processing line, marking a critical step towards full-scale production.

To ensure compliance with stringent quality standards, Ecolomondo conducted extensive in-house testing using advanced laboratory equipment. Key parameters, including humidity, pellet size, pellet hardness, ash content and particle size, were meticulously evaluated. After confirming that all specifications were met, the company shipped rCB samples to offtake clients for independent verification. The clients’ test results aligned closely with Ecolomondo’s own findings, validating the material’s high quality.

In response to this successful validation, the primary offtake client placed an initial order for 23 metric tonnes of rCB, which Ecolomondo is preparing to ship immediately. At full operational capacity, the Hawkesbury facility is projected to recycle between 1.3 million and 1.5 million scrap tyres annually, yielding approximately 4,000 metric tonnes of rCB, 5,000 metric tonnes of pyrolysis oil, 2,000 metric tonnes of steel and 1,200 metric tonnes of process gas. This milestone underscores Ecolomondo’s leadership in sustainable tyre recycling and reinforces the commercial viability of its TDP technology.

Jean- François Labbé, Interim CEO of the Company, said, “The commercial acceptance of our rCB by offtake clients reflects the achievement of many years of technology development and commitment. It is a major achievement for the Company and we are confident that additional orders should come because of the quality of our rCB.”

CARBIOS has signed a multi-year commercial agreement with Indorama Ventures, the world’s leading PET producer, to supply biorecycled monomers from its Longlaville plant. Indorama will repolymerise these monomers into r-PET filaments, which Michelin will then integrate into its tyre reinforcements.

Using its proprietary enzymatic recycling technology, CARBIOS will process complex PET waste into high-purity monomers at its new facility. Indorama will handle the conversion of these monomers into technical-grade filaments, enabling Michelin to enhance the sustainability of its tyres. This partnership accelerates the pre-commercialisation phase of CARBIOS’ industrial project, building on recent contracts with two major cosmetics brands for biorecycled PET.

The collaboration highlights the growing demand for circular solutions in manufacturing, with CARBIOS’ innovation playing a pivotal role in transforming waste into high-value materials. This milestone reinforces CARBIOS’ position as a leader in enzymatic recycling and supports Michelin’s commitment to sustainable mobility.

Vincent Kamel, CEO of CARBIOS, said, “This commercial agreement with Indorama Ventures marks a new step in the realisation of our industrial project. It confirms the trust of Indorama Ventures and Michelin in our PET biorecycling technology. Alongside the commercial successes already achieved in cosmetic packaging applications, this agreement illustrates our ability to deliver innovative solutions to the most demanding industries, particularly industrial filaments for tyre applications and, more broadly, textile.”

Fabien Gaboriaud, Director of Circularity and Renewable & Recycled Materials at Michelin Group, said, “This partnership is a tangible expression of our commitment to turning complex waste into high-performance materials. By integrating enzymatically recycled r-PET into our tyres, we are marking a new milestone on our journey toward achieving 100 percent renewable and recycled materials by 2050 — all while staying within planetary boundaries. It is by combining innovation, industrial excellence and close collaboration with trusted partners that we are building a strong and lasting circular model.”

Renato Boaventura, Global Market Head – Mobility at Indorama Ventures, said, “This alliance with both, CARBIOS and Michelin, underlines our commitment to plan ahead and take a leading role in shifting the industry towards circularity.”

Wind, a leading financial data provider, has released its 2025 ESG (Environmental, Social and Governance) ratings, showcasing notable improvements for several listed companies under Sinochem Group. The ratings reflect these companies' strong commitment to sustainable development and corporate responsibility.

Sinochem International achieved an AA rating in 2025, a significant improvement from its previous rating in 2024. With a comprehensive score of 8.56 out of 10, the company now holds the highest ESG rating in the diversified industrial sector, setting a new record among Sinochem Group’s listed companies. Sinochem Equipment and Shenyang Chemical also demonstrated substantial progress, with both companies upgrading from a BBB rating in 2024 to an A rating in 2025. These improvements underscore the group-wide advancements in sustainability practices.

The upgrades highlight Sinochem Group’s intensified focus on sustainability initiatives, including enhanced environmental compliance, green transition efforts, stronger corporate governance and improved transparency. Additionally, the companies have made strides in social responsibility programmes, such as worker welfare and community engagement.

The ESG rating jumps for Sinochem International, Sinochem Equipment and Shenyang Chemical underscore Sinochem Group’s leadership in sustainable business practices. As China continues to push for carbon neutrality and ESG integration, these companies are well-positioned for long-term growth and resilience.

Covestro has introduced its next-generation Baysafe BEF flame-retardant polyurethane foam, a breakthrough in EV battery safety. Designed to prevent thermal runaway propagation between cells, this lightweight foam meets stringent global safety demands, particularly in China, where the new GB 38031-2025 standard will require fireproof batteries from 2026.

As the world’s largest EV market, China’s regulations are expected to influence global standards, making Covestro’s innovation critical for automakers. The foam’s superior flame resistance enhances safety in EVs, e-bikes and portable energy storage, addressing a key consumer concern. By combining cutting-edge flame-retardant technology with lightweight performance, the Baysafe BEF series helps drive the transition to sustainable transportation and energy storage worldwide.

With EV adoption accelerating, Covestro’s material solutions support manufacturers in meeting stricter safety requirements while enabling international expansion. Beyond encapsulation, the company offers polyurethane-based battery covers and shock-absorbing components, strengthening its position in the fast-growing new energy sector.

Akhil Singhania, Global Head of PU Specialties in Covestro’s Tailored Urethanes Business Entity, said, “This innovation represents a significant step towards enabling sustainable mobility through enhanced safety. By launching our advanced flame-retardant technology, Covestro reaffirms its commitment to innovation and strengthens our product portfolio to meet the evolving needs of the EV industry.”