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 Association of Natural Rubber Producing Countries (ANRPC) published its Monthly Natural Rubber Statistical Report for August 2026, noting firmer prices in several markets. Supply constraints, stable downstream demand and persistent geopolitical and macroeconomic uncertainty shaped the month. Renewed conflict and disruptions to major shipping routes added further pressure.

Physical prices for major grades moved in different directions. SMR-20 in Kuala Lumpur averaged USD 2.31 per kg, up 4.25 percent from July, while STR-20 in Bangkok rose 1.40 percent to USD 2.39 per kg. RSS-3 dropped 4.18 percent to USD 2.80 per kg, but RSS-4 in Kottayam gained 0.57 percent to USD 2.92 per kg. Latex-in-bulk fell 4.73 percent to USD 1.73 per kg. Brent crude averaged USD 91.08 per barrel, driven by concerns over possible restrictions on oil shipments through the Strait of Hormuz and wider Middle East instability, which raised energy supply risks and strengthened the oil market risk premium.

On trade, China's imports climbed 3.39 percent month-on-month, while India fell 10.18 percent and Malaysia dropped 8.24 percent; Viet Nam rose 5.08 percent. Exports advanced 5.63 percent in Viet Nam but declined in Thailand (-5.24 percent), Indonesia (-5.36 percent), Malaysia (-1.48 percent) and Cambodia (-1.88 percent).

Global production is projected to rise 0.6 percent to 15.039 million tons in 2026 from 14.952 million tonnes in 2025, after revisions to Thailand's 2025 output and updated 2026 estimates for Thailand, Malaysia and Indonesia. Weather, including erratic rainfall and drier Southeast Asian conditions, affected output. August 2026 production was estimated at 1.396 million tonnes, down 4.51 percent from 1.462 million tonnes a year earlier. Demand is forecast to grow 0.4 percent to 15.356 million tonnes in 2026 from 15.301 million tonnes, with the largest consumption gains expected in China, Malaysia and Cambodia. Prospects depend on vehicle sales, tyre production, shipping conditions and weather-related supply disruptions, while steady EV-linked demand supported modest growth led by China and India. The ringgit traded between RM4.02 per USD and RM4.09 per USD, and the baht between 32.68 and 33.34. The SHFE January 2027 contract averaged 18,109 CNY per tonne, up 7.78 percent month-on-month, while the SGX November 2026 contract averaged USD 2.24 per kg, up 4.32 percent.

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HS HYOSUNG has formalised a memorandum of understanding (MoU) with the State Government of San Luis Potosí, with the signing taking place at the World Trade Center Mexico City. The event formed part of the Korea-Mexico Business Forum, held alongside the Korean economic delegation's visit to Mexico.

Attending officials included Marcelo Ebrard, Mexico's Secretary of Economy, and Mario García Valdez, Secretary of Economic Development of San Luis Potosí. The two sides confirmed their shared resolve to back the company's local investment and regional growth. Separately, HS HYOSUNG's leadership met bilaterally with Secretary Ebrard to elaborate on its strategic vision and investment plans.

The agreement sets out a phased expansion of HS HYOSUNG's investments in San Luis Potosí beginning in 2027, with the goal of creating a major advanced materials production hub that bolsters supply for North American and wider global markets. The company's advanced materials span tyre cord, a flagship world-leading product, along with mobility, energy, aerospace and defence applications. Its North American operations, spanning Mexico and the United States, turn out tyre cord, airbag materials and mobility interior components for global leaders such as General Motors and Goodyear, underpinned by a highly dependable global supply chain.

Nak-yang Sung, CEO, HS HYOSUNG ADVANCED MATERIALS, said, “This investment goes beyond establishing a simple manufacturing base – it reflects our strategy to turn Mexico into a pivotal hub connecting North America with global supply networks. We are also committed to strengthening local supply chains and creating high-quality jobs to contribute directly to the region's industrial ecosystem.”

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Kumho Petrochemical Group is steering its business towards research-driven, higher-value outputs as oversupply and soft demand continue to weigh on the worldwide petrochemical sector. The Seoul-based group outlined plans to boost spending on speciality chemicals, sustainable materials and novel production methods, a push intended to lift profits while building a foundation for future expansion.

Underlying the move is a deliberate evolution in the group's identity, from a bulk materials vendor to a provider of technology-backed solutions that address shifting customer requirements and stricter environmental rules. A central element of that effort involves widening the speciality lineup, exemplified by added capacity for solution styrene butadiene rubber, a synthetic rubber that enhances durability, rolling resistance and tread wear in high-performance electric vehicle tyres.

Environmental initiatives form another pillar. Facilities built by the company can trap approximately 76,000 metric tonnes of carbon dioxide each year, while separately developed technology turns recycled acrylonitrile butadiene styrene sourced from scrapped household appliances into automotive-grade interior components that satisfy performance standards and generate fewer emissions than conventional methods. The group has also joined forces with POSCO Future M and BEI on anode-free lithium-metal battery development.

Parallel technology-focused programmes are underway at affiliated units. Kumho P&B Chemicals is formulating water-based epoxy resins that curb volatile organic compound releases while incorporating more bio-based inputs to reduce carbon intensity. Kumho Mitsui Chemicals is advancing bio-based polyurethane systems and electric vehicle materials, alongside debottlenecking work to add 100,000 tonnes of annual methylene diphenyl diisocyanate capacity. Kumho Polychem, meanwhile, is targeting ethylene propylene diene monomer through low-temperature polymerisation paired with energy-efficiency improvements.

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Birla Carbon has confirmed a price increase of up to 15 percent for its Speciality Materials products across Asia, scheduled to take effect on 1 October 2026. The company pointed to significant and sustained rises in feedstock costs, driven partly by ongoing geopolitical instability and disruptions in global feedstock markets, as the reason behind the adjustment.

Although Birla Carbon pursued operational efficiencies, supply chain optimisation and disciplined cost management to soften the impact, the scale and persistence of the cost escalation left a price adjustment unavoidable. The company's sales teams will engage customers directly to explain the details and help them navigate the transition.

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