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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Europe’s tyre industry stands at a crossroads as mounting regulatory pressure, resource constraints and circular economy targets reshape the end-of-life tyre landscape. Despite Germany achieving one of the world’s highest recycling rates, an estimated 100,000 tonnes of used tyres continue to leave the country annually, undermining domestic recovery efforts. In conversation with Tyre Trends, AZuR Network Coordinator Anna-Maria Guth outlines the policy reforms, recycling technologies, retreading opportunities and cross-border collaboration needed to keep valuable raw materials in circulation and build a fully circular European tyre ecosystem.

What gaps in the traditional tyre value chain led to the establishment of the AZuR network?

In Germany, we have a very high recycling rate for end-of-life tyres. However, following a merger of certified tyre disposal companies that collect and sort tyres, it became clear that we needed to bring all stakeholders together to really make progress. The excellent response to the AZuR network shows that this is the right approach.

The European tyre industry is under increasing pressure regarding emissions, waste management and the circular economy. What policy measures are still needed to accelerate the widespread adoption of tyre recycling?

Couple of policy implementations must be achieved in order to reach this goal. The first is a strict ban on the export of ELTs and rigorous enforcement of this regulation. Secondly, clear, predictable and statutory regulations regarding the use of ELT granulate. Lastly, consistent implementation of circular economy strategies.

What role can recovered carbon black (rCB) play in reducing Europe’s dependence on primary fossil raw materials?

The pyrolysis companies in the AZuR network are making great strides in improving the quality of rCB. We are optimistic that in the foreseeable future, we will be able to produce a grade that allows the material to be incorporated into new tyres in larger quantities. That would be a major breakthrough and would create real added value as it would keep the raw materials within the circular economy.

How does AZuR distinguish between mechanical recycling, devulcanisation and pyrolysis in terms of sustainability and scalability?

Within the network, we adhere to the European waste hierarchy viz-a-viz prevention, reuse, recycle including mechanical and chemical and, finally, thermal recycling.

We are open to all technologies when it comes to processes. However, it is clear that in the interests of the circular economy, we want to minimise thermal recovery. And this also applies to pyrolysis oil provided it is not used for the production of new products but as a secondary fuel.

How close is the tyre industry to establishing tyres made with recycled materials without compromising on performance?

Some manufacturers are already field-testing tyres containing over 70 percent recycled and bio-based raw materials. The industry is very active in this area. However, we would like to see a more nuanced approach to recycled materials and bio-based materials.

Bio-based materials cannot be the solution in the medium term and the EUDR is already restricting the use of bio-based materials in Europe. Our focus must be more on recycled materials and their qualities so that raw materials can be kept in the cycle.

More than 500,000 tonnes of end-of-life tyres are generated in Germany every year. What are currently the biggest bottlenecks in the infrastructure for collection, sorting and processing?

At present, the SME sector in Germany is structured in such a way that all tyres generated can be collected, sorted and processed. Our biggest challenge is that the material is currently being exported rather than ending up with responsible companies in the circular economy. We estimate that around 100,000 tonnes are exported annually without proper regulation.

How will the network influence future EU regulations on the circular economy?

We are delighted to be engaging in growing dialogue with EU bodies, which enables us to raise the profile of the circular economy, which is dominated by small and medium-sized enterprises. Our aim is to set the right course at European level as quickly as possible so that companies can work successfully with the materials and keep as many raw materials as possible in the cycle.

Which groundbreaking technologies or business models are currently attracting the most attention?

There are quite a few, and to name just a few, we have companies in the network working on AI-driven solutions for tyre sorting as well as start-ups producing devulcanised materials for the new tyre industry or AI-assisted machines for the professional regrooving of truck tyres.

How important is cross-border cooperation in establishing a sustainable circular economy for tyres across Europe, rather than in isolated national markets?

AZuR started as a German network, but we can now safely say that we have become a European network. We have partners from Italy, the Netherlands, Austria, Ukraine, Estonia and Poland. All these countries face similar challenges as the relevant legislation is often decided at European level and we can achieve very little at national level. We can only take the big steps together in Europe.

How difficult is it to reconcile economic interests within such a diverse ecosystem?

All AZuR partners are united by a shared vision of 100 percent recycling of end-of-life tyres generated in Europe. We know that this is economically viable. However, we also know that we can only tackle the hurdles that are currently preventing us from reaching our goal by working together.

Our target of 100 percent recycling of end-of-life tyres is very realistic and, in our view, can be achieved in the short term with the right measures.

How do you respond to the market’s ongoing concerns regarding the safety, quality and performance of retreaded tyres?

The retreaders currently operating in Germany are industrial retreaders whose quality standards are in no way inferior to those of new tyre manufacturers. Real-world use shows that there are no quality limitations with retreaded tyres. When retreaded, the casings from premium manufacturers offer a quality comparable to that of the original new tyre.

Incidentally, the safety of the technology is demonstrated by retreaders of aircraft tyres as such tyres are retreaded 12 to 14 times and are highly relevant to safety. And retreading is the ideal solution for recycling as it allows the tyre to be used a second and third time as a tyre.

Why has retreading uptake in the passenger car sector remained relatively limited compared to that in the commercial vehicle sector?

One of the major challenges facing retreading in the passenger car sector is the vast variety of sizes, which makes retreading economically unviable. We are constantly seeking dialogue with vehicle manufacturers on this issue.

Furthermore, passenger car tyres are often in use for longer because they are driven less frequently, meaning fewer casings are available for retreading. However, we believe in passenger car tyre retreading, particularly given the growing share of electric vehicles, and are delighted that a retreader in Germany will be relaunching operations in this segment this year.

How important will AI, predictive analytics and sensor-based tyre management become over the next decade?

Smart tyre management is both an economic factor for haulage companies and an environmental one. We know that how a tyre is used has a significant impact on its service life. And at the top of the waste hierarchy is waste prevention. Here, both the new tyre industry and users are called upon to make optimal use of tyres so that they can remain in service for as long as possible.

What would success look like for AZuR in the next five years?

We would have reason to celebrate if we were to achieve the following key objectives in the coming years. The objectives include 40 percent market share for retreaded lorry tyres in Europe, 10 percent market share for retreaded passenger car tyres in Europe, 100 percent recycling of end-of-life tyres in Europe and clear legal regulations governing the use of recycled ELTs.   

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Epsilon Carbon has significantly expanded its manufacturing footprint with the formal activation of a new 300,000-tonne-per-annum speciality carbon plant in Vijayanagar, Karnataka. This latest addition brings the company’s aggregate production capacity in this segment to 600,000 tonnes annually, a development that elevates the firm to a leading position among domestic producers and reinforces India’s broader influence in the international speciality carbon market.

The new installation operates on a fully digitised manufacturing architecture, incorporating real-time process monitoring, automated quality controls and interconnected production systems. Such technological integration is intended to minimise operational variability, maximise throughput and provide overseas buyers with a stable and predictable supply base across multiple product categories.

Output from the Vijayanagar complex will encompass a wide array of coal-tar derivatives, including binder and impregnated pitches, refined naphthalene, anthracene and creosote oils and wash oil. These intermediates find application across a spectrum of heavy and light industries, ranging from primary aluminium and graphite electrode production to tyre compounding, pigment formulation, pharmaceutical synthesis and speciality construction materials.

Looking ahead, the company has outlined a trajectory towards further capacity enhancement, with a proposed integrated facility in Jharsuguda, Odisha, expected to push total speciality carbon output to one million tonnes per annum by the end of the decade. Meanwhile, the Karnataka plant has been configured with closed-loop water management, recycling all treated effluent internally, and derives its entire power requirement from a 17‑megawatt captive unit running on recycled process off-gases. Certifications such as Responsible Care, EcoVadis Silver and SA8000 attest to the company’s adherence to stringent safety, environmental and labour standards.

Gaurav Mathur, Chief Executive Officer, Epsilon Carbon, said, "This expansion reflects India's growing capability to become a global supplier of speciality carbon materials. With 600,000 TPA of Speciality Carbon capacity, we are strengthening supply chain resilience for both domestic industries and international customers, particularly the global aluminium sector. As the world looks to diversify supply chains, Epsilon Carbon is proud to contribute to India's emergence as a reliable, sustainable and globally competitive manufacturing hub."

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HS HYOSUNG ADVANCED MATERIALS participated in the China Composite Expo 2026 (CCE 2026), held at the National Exhibition and Convention Center in Shanghai from 1 to 3 September. This annual event stands as Asia’s largest specialised exhibition for composite materials, drawing a significant global audience.

The company has been a consistent participant in CCE since 2013, leveraging the expo to progressively reinforce its foothold in the Asian market. At this year’s showcase, the strategic focus was on its portfolio of high-performance carbon fibre products, which are increasingly recognised as essential materials for advanced sectors including energy, mobility and aerospace due to their superior tensile strength and modulus.

Central to the presentation were actual samples of TANSOME, the company’s proprietary carbon fibre brand developed through in-house technologies. The exhibit featured a diverse range of applications, from mobility components like automotive wheels, hoods and brake discs to sporting goods such as hockey sticks and pickleball rackets, as well as high-pressure vessels for hydrogen and oxygen, drones and wire cores.

In parallel, HS HYOSUNG ADVANCED MATERIALS emphasised its robust manufacturing capabilities and stable supply chain, supported by production bases in Korea, China and Vietnam. This strategy reinforces its standing as a leading global carbon fibre manufacturer. Notably, the company achieved a milestone in 2011 as the first in Korea to independently develop TANSOME, a material 4 times lighter and 10 times stronger than steel. This was followed by the 2022 launch of H3065, a T-1000-grade fibre with strength exceeding steel by over 14 times, designed for demanding aerospace applications.

Jin Dal Lim, CEO, HS HYOSUNG ADVANCED MATERIALS, said, “This exhibition is an important opportunity to further strengthen strategic partnerships with global customers and demonstrate the outstanding technological capabilities of HS HYOSUNG’s carbon fibre. We will continue to build deeper trust in the global market based on world-class product quality and stable supply capabilities.”

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Bekaert has taken a decisive step towards reshaping its operational footprint in Sardinia by securing a preliminary deal with Nuova Icom, a local engineering entity. The arrangement paves the way for the handover of the Macchiareddu premises and guarantees job continuity for the existing staff stationed there, subject to the final stipulations of the contract.

The decision stems from long-term turbulence in the tyre sector, which has steadily undermined the commercial viability of the plant's primary output. With tyre cord manufacturing struggling to remain profitable amidst evolving industry dynamics, the company concluded that a fundamental operational shift was unavoidable.

This initiative follows an extensive search for sustainable alternatives, emphasising regional employment preservation. Bekaert remains attuned to the social ramifications of the transition and pledges to engage transparently with all affected parties. The prospective ownership change is scheduled for completion by October 2026, pending regulatory clearances and the finalisation of employee consultations.

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