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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As Extended Producer Responsibility (EPR) frameworks expand globally, the tyre industry is undergoing a structural transformation. Collection systems are improving, traceability is increasing and investments in recycling technologies are accelerating. However, one critical tension remains insufficiently addressed: the speed of industry evolution is outpacing the agility of public policy. And within that gap, one key question emerges: where does retreading fit in this new circular economy architecture?

A STRUCTURAL PARADOX

Retreading represents one of the most efficient forms of resource optimisation in the tyre lifecycle. It extends product life, reduces raw material consumption and lowers emissions. Yet, in many regulatory frameworks, it is still treated ambiguously – often grouped with recycling rather than recognised as prevention or preparation for reuse. This distinction is not semantic. It is strategic. Because when policy fails to differentiate, markets fail to prioritise.

A FAST-MOVING INDUSTRY, A SLOW-MOVING FRAMEWORK

The tyre market is evolving in real time:

1. Increasing penetration of low-cost imports.
2. Growing variability in product quality.
3. Accelerated turnover cycles.

Retreading, in this context, becomes more than a circular solution. It becomes a filter of industrial quality. Not all tyres are equally retreadable. And that difference defines their real contribution to circularity. Yet most EPR systems continue to operate with uniform economic signals, failing to distinguish between products that enable multiple lifecycles and those that exit the system after a single use.

SIGNALS FROM EUROPE

Recent developments in countries like Portugal – where eco-fees applied to retreaded tyres approach those of low-cost, non-differentiated new tyres – highlight a concerning trend. Similarly, in Spain, industry representatives continue to advocate for a clearer institutional recognition of retreading within EPR systems. These cases illustrate a broader issue: circular policies can unintentionally undermine higher-value circular strategies.

THE MISSING LINK: PERFORMANCE-BASED POLICY

What is missing is not regulation. It is regulatory precision. EPR systems have successfully organised waste flows. But they have not yet evolved to reward performance within the lifecycle. This is where eco-modulation becomes critical.

ECO-MODULATION AS A STRATEGIC LEVER

Eco-modulation should not be a marginal adjustment. It should be a core industrial policy tool. Properly designed, it can:

• Differentiate tyres based on real circular
• performance.
• Incentivise durability and retreadability.
• Penalise short-lifecycle, non-recoverable products.
• Align market behaviour with system objectives.
• To operationalise this, we need new metrics.

FROM COMPLIANCE TO PERFORMANCE: A PROPOSED FRAMEWORK

The next step for EPR systems is to move towards performance-based differentiation. This could be implemented through instruments such as:

• Retreadability Index (RI)
• Performance Score (CPS)

These would measure:

• Number of effective retreading cycles per tyre.
• Structural durability and casing quality.
• Real contribution to lifecycle extension.

Under such a system:

• Tyres with higher retreadability would receive lower eco-fees.
• Products that systematically fail to re-enter the cycle
• would face higher costs.
• This is not just a technical refinement. It is a shift from:
• Generic compliance.
• To intelligent market shaping.

THE LATIN AMERICAN PERSPECTIVE

In Latin America, the stakes are even higher.

The region faces:

• Structural dependence on imported tyres.
• Strong presence of low-cost, low-durability products.
• Emerging EPR frameworks (Chile, Costa Rica, Peru, Ecuador)

Chile, for example, through its EPR law (Ley REP), has made significant progress in structuring collection and recovery targets. However, like many systems, it still faces the challenge of fully integrating reuse strategies into its economic logic. Under these conditions, retreading is not just an environmental solution. It is a strategic industrial capability.

BEYOND WASTE MANAGEMENT

Latin America has a unique opportunity to design EPR systems not only to manage waste

but to govern resources and shape markets.

This means:

• Incentivising retreadable tyres
• Strengthening local retreading industries
• Reducing dependence on short-lifecycle imports
• Building resilience into supply chains

But this requires something critical: policy agility. Because if regulation lags behind market dynamics, it will not transform the system – it will merely formalise its inefficiencies.

A STRATEGIC CONCLUSION

If EPR systems are designed without properly integrating retreading – and without differentiating based on actual circular performance – they risk reinforcing a linear logic under a circular narrative. For emerging regions, this would be a critical mistake

The discussion around repair, reuse and retreading can no longer be treated merely as a waste management issue. It is increasingly becoming a matter of industrial resilience, strategic autonomy and economic security.

As global supply chains face growing pressure from geopolitical fragmentation, logistics disruptions and volatility in raw material markets, extending the useful life of products is emerging as a strategic capability for nations and industries alike.

In this context, Right to Repair should not be understood only as a consumer right but also as an industrial policy tool capable of strengthening local economies, reducing external dependency, preserving technical capabilities and supporting more resilient production systems.

Retreading, remanufacturing and reuse are part of a broader transition where value creation is no longer based exclusively on extraction and disposal but increasingly on intelligence, efficiency and lifecycle management.

CIRCULARITY WITHOUT HIERARCHY BECOMES INEFFICIENCY. REGULATION WITHOUT DIFFERENTIATION BECOMES DISTORTION.

Final note

The future of the tyre industry will not be defined only by how we recycle, but by how intelligently we extend the life of what we already produce. And that requires alignment between:

• Industry dynamics.
• Policy design.
• And strategic vision.

In that equation, retreading must move from the margins to the centre. Because properly understood, it is not just a process. It is a strategic filter, an industrial policy tool and a geopolitical lever.

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The Association of Natural Rubber Producing Countries (ANRPC) has released its market report for May 2026, depicting a sector characterised by sustained price strength and firm fundamentals. The global natural rubber market received additional upward momentum from a decline in Brent crude oil prices, which averaged USD 107.14 per barrel during the month. This represented a month-on-month decrease of 8.65 percent, attributed to easing geopolitical tensions in the Middle East and the temporary reopening of the Strait of Hormuz, which collectively bolstered the commodity's outlook.

Global production projections for 2026 stand at 15.337 million tonnes, marking a 2.4 percent increase from the previous year, with growth driven by Thailand, China, India and Malaysia, even as output moderates in Indonesia and Vietnam. Monthly production, however, fell to 997,000 tonnes in May, a year-on-year decline of 4.7 percent, due to seasonal wintering and dry weather conditions across South and Southeast Asia. Concurrently, worldwide consumption is forecast to rise by 1.3 percent to 15.550 million tonnes for the year, with May's consumption reaching 1.310 million tonnes, a 4.6 percent annual increase. This demand was underpinned by steady tyre manufacturing, electric vehicle-related consumption and resilient purchasing managers' indices in China and India, alongside record auto retail sales in India.

Physical prices for all major grades recorded broad-based gains throughout May, with SMR-20, STR-20, RSS-3, RSS-4 and latex all experiencing increases. Trade flows showed a mixed pattern, as imports from China and India contracted month-on-month, while Malaysia and Vietnam registered significant gains. On the export front, Cambodia, Vietnam and Thailand recorded increases, whereas Indonesia and Malaysia saw declines. Currency movements saw the Malaysian ringgit ease slightly, while the Thai baht traded within a stable range, and both nations reported decelerating GDP growth for the first quarter of 2026. Futures contracts on the SHFE and SGX reflected tightening supply and firm demand, posting notable month-on-month gains.

The market outlook remains cautiously balanced against a backdrop of several macroeconomic factors. Elevated trade tensions between United States and China, ongoing geopolitical conflicts and a steady United States Federal Reserve interest rate policy present potential headwinds. However, these are being offset by supportive elements, including the accelerating adoption of electric vehicles, tight feedstock supply due to adverse weather and the positive market sentiment generated by the European Union's decision to lower anti-dumping duties on Chinese tyres.

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Zeon Corporation has introduced a novel data management system specifically designed for elastomer research and development, marking the company’s first foray into a subscription-based service model. The platform is engineered to centralise and streamline R&D data pertaining to rubber products, with the primary goal of enhancing operational efficiency and accelerating developmental processes for its clientele. The initial phase of the rollout will concentrate on the Japanese market, with a strategic plan to broaden access to other regions in the future.

The elastomer industry frequently grapples with the fragmentation of data across disparate systems, which complicates the effective utilisation of historical information. Through extensive experience in elastomer supply and sustained client engagement, Zeon has identified this operational hurdle as a pervasive issue affecting the entire sector. This recognition has been the catalyst for developing a solution that directly confronts these data management deficiencies.

The newly launched system incorporates specialised functionalities that are finely attuned to the nuances of rubber product R&D. It integrates a comprehensive database that combines master data for key compounding agents available in Japan with extensive catalogue information, facilitating rapid and efficient data access for daily research tasks. The platform’s intuitive interface and user experience are meticulously crafted to optimise usability and data visualisation, with a commitment to ongoing enhancements based on evolving customer requirements.

Zeon has formally designated this data management solution as a growth driver for its strategic initiatives, extending beyond the Phase 3 objectives of its STAGE30 medium-term plan. The company envisions this business becoming a cornerstone of its strategy to augment the value proposition of its elastomer operations. By synergising its deep-seated elastomer expertise with advanced data utilisation technologies, Zeon is poised to foster innovation in client R&D and propel the overall advancement of the elastomer industry.

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A new bio-based cut & chip resin for the most demanding applications.

NaugaShield BIO-TR 30 is SI Group’s latest advancement in bio-based performance resins designed to significantly improve cut and chip resistance in high-severity rubber applications. With approximately 75 percent bio-based content, this innovative material delivers on sustainability targets while exceeding the performance typically associated with petroleum-derived resins, making it a strong choice for applications such as OTR tyres in mining, construction and agriculture, mining conveyor belts, rubber tracks and mill linings.

Cut and chip resistance is a complex set of material behaviours, including static mechanical strength, dynamic response under deformation and ability to withstand sharp impacts and abrasive environments. In demanding applications such as mining or agriculture, materials must tolerate repeated high-strain loading and resist the initiation and propagation of tears. NaugaShield™ BIO-TR 30 was developed precisely to meet these conditions, demonstrating notably low dynamic heat buildup and excellent tear strength – characteristics closely tied to enhanced cut and chip resistance and long-term durability under cyclical loads.

To evaluate its performance, NaugaShield BIO-TR 30 was benchmarked in an Off-road Rib Tread formulation against two widely used industry references: a gum rosin/semi-aromatic C5/C9 resin combination and a styrenated DCPD resin. All materials were tested at an equal loading of 10 phr to provide a direct and unbiased comparison. Under these conditions, the bio-based resin consistently outperformed both alternatives, offering a stronger balance of reinforcing behaviour, improved tear propagation resistance and superior resistance to thermal degradation during dynamic flexing. Further improvements were achievable by reducing the amount of free extender oil in the compound, underscoring the resin’s adaptability in formulation design and its ability to unlock even greater performance when optimised.

These laboratory indicators were corroborated through extended Coesfeld Cut & Chip testing (see chart), in which compounds were subjected to up to 3,000 cycles at 200 rpm under a 200N applied force. Formulations containing NaugaShield BIO-TR 30 exhibited substantially lower mass loss and maintained tread surface integrity more effectively than the hydrocarbon and gum rosin-based-benchmarks. The performance advantage was even more pronounced in compounds adjusted for lower free oil content, confirming that the resin can be tailored to meet the durability requirements of the most challenging operating conditions.

The strong performance of NaugaShield BIO-TR 30 in OTR tread compounds can be readily transferred to other rubber goods that encounter similar wear mechanisms. Applications such as mining belts, agricultural and construction tracks or mill linings benefit from the resin’s ability to reinforce the rubber matrix, reduce crack growth under repeated impact and maintain structural cohesion under high-strain deformation. This versatility allows manufacturers to integrate a 75 percent bio-based resin that supports sustainability by reducing fossil-based content and helping end products last longer while maintaining – and often improving – operational performance across multiple product lines.

NaugaShield BIO-TR 30 is currently available in commercial quantities, enabling compounders and manufacturers to move directly from laboratory evaluation to pilot- and production-scale trials.

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