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 German Rubber Industry Association (wdk) has sounded an alarm over an exceptionally difficult economic situation facing the rubber sector. Soaring raw material prices and persistently high energy costs, exacerbated by the Iran war, are coinciding with weak industrial demand. wdk Chief economist Michael Berthel noted an almost unprecedented economic disparity, as raw material costs approach historical highs from 2011 and 2022 while a lack of demand prevents any offset for manufacturers.

Since the final quarter of 2025, prices for key inputs have risen sharply. Natural rubber has jumped more than 40 percent within months, while butadiene-based synthetic rubbers have increased over 30 percent. EPDM synthetic rubber, carbon black and oil-based plasticisers have all risen more than 20 percent, with some individual chemicals exceeding 40 percent cost growth in just a few weeks.

Energy prices remain a major burden, with Middle East developments fuelling market uncertainty. Risks to international transport and supply chains persist, and German rubber companies are closely watching potential impacts on raw material availability and global logistics flows.

Berthel warned that firms face mounting pressure from high costs, geopolitical instability and structural disadvantages in Germany, with no short-term relief in sight. The industry depends heavily on fair and reliable partnerships across the value chain, as processing companies alone cannot absorb the current strain. He called for fair solutions and a shared understanding of this exceptional situation.

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The Rubber Board of India has confirmed the continuation of all existing central sector schemes for the 2026-27 fiscal year at unchanged rates. Financial aid for new planting will be restricted to estates utilising poly bag or root trainer plants sourced solely from Board-approved nurseries, with applicants required to submit the original purchase bill. This mandatory verification step aims to ensure quality and authenticity of planting materials used across the sector.

Support for rain guarding and spraying operations will be channelled exclusively through Rubber Producers’ Societies. These societies must include GST bills for all acquired materials when applying. The official timeline for submitting applications will be announced separately by the Board, giving producers adequate time to prepare documentation and coordinate with their respective societies before the deadline.

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The Rubber Board of India has announced a temporary engagement for a young professional within its Market Promotion Division, located at the RRII campus in Puthuppally, Kottayam. The selected individual will assist with division activities and promote ‘mRube’, the electronic trading platform for natural rubber.

Candidates must hold an MBA in Marketing or Agri Business Management with computer knowledge, while skills in digital marketing, sales or market research and proficiency in English and Hindi are preferred. Applicants aged up to 30 years as of 1 May 2026, will be considered for the one-year role, which offers a consolidated monthly pay of INR 25,000.

Interested individuals should send their applications to the Deputy Director (Marketing) at the Central Laboratory Building, RRII, Rubber Board PO, Kottayam – 686009 by 19 May 2026. Shortlisted names will appear on the Rubber Board’s website with interview details, as no separate communication will be sent.

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Bekaert has officially finalised its acquisition of Bridgestone’s tyre reinforcement operations in China and Thailand, after securing all necessary regulatory approvals and meeting standard closing conditions. The deal, now fully completed, marks a significant step in the Belgian company’s expansion strategy.

The transaction brings under Bekaert’s control two production facilities: Bridgestone (Shenyang) Steel Cord Co., Ltd. in China and Bridgestone Metalfa (Thailand) Co., Ltd. in Thailand. These plants specialise in manufacturing high-quality tyre cord products exclusively for Bridgestone tyres, and they will continue to supply Bridgestone under the new ownership, further deepening the longstanding partnership between the two firms.

Financially, the acquisition is expected to add roughly EUR 80 million to Bekaert’s annual consolidated sales. The EUR 60 million cash consideration for the deal was funded from the company’s available cash reserves.

Curd Vandekerckhove, CEO Rubber Reinforcement, said, “With the completion of this acquisition within our Rubber Reinforcement division, we are pleased to officially welcome the plant teams in China and Thailand to Bekaert. Our immediate focus is on a smooth transition and operational continuity while continuing to serve Bridgestone as a key strategic partner. The completion of the acquisition further strengthens the position of Bekaert in the tyre cord market, expands the global manufacturing footprint and deepens our longstanding partnership with Bridgestone. A long-term supply agreement ensures continued delivery of high-quality tyre reinforcement within a trusted supplier model.”

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