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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India has launched an anti-dumping investigation into imports of Halo-Isobutene-Isoprene Rubber (HIIR) from China, Singapore and the United States, following a complaint from Reliance Sibur Elastomers Private Limited, the Directorate General of Trade Remedies (DGTR) said in a notification.

The domestic producer alleged that the three countries were exporting the rubber to India at unfairly low prices, causing injury to the local industry. The company has sought the imposition of anti-dumping duties on the product, which is used in tyre inner liners, hoses, seals, tank linings, conveyor belts and protective clothing.

The DGTR said there was prima facie evidence that imports had risen “significantly” and were being sold below normal value, resulting in price depression and affecting the domestic manufacturer’s capacity utilisation and profitability. The authority noted that the dumping “is causing material injury to the domestic industry”.

The investigation will cover the period from July 2024 to June 2025, with an examination of injury trends dating back to April 2021.

HIIR, also known as halobutyl rubber, is classified under the broader synthetic rubber tariff category. Reliance Sibur Elastomers is currently the only producer of the material within India.

If the investigation confirms dumping and injury, the DGTR may recommend the imposition of duties to offset the impact and “remove the injury to the domestic industry”. Interested parties have 30 days to submit data and make their representations to the authority.

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The global carbon black market is projected to grow from USD 27.88 billion in 2024 to USD 44.77 billion by 2034, expanding at a compound annual growth rate (CAGR) of 4.85 percent between 2025 and 2034, according to a new report by Towards Chemical and Materials, a research arm of Precedence Research.

The study estimates that the global market volume will rise from around 15.15 million tonnes in 2025 to 21.83 million tonnes by 2034, growing at a CAGR of 4.14 percent, driven primarily by increasing demand for tyres, automotive components and high-performance plastics.

Carbon black – a fine black powder made through the incomplete combustion of hydrocarbons – is a critical material used to reinforce rubber in tyre production and enhance strength, durability and UV resistance in plastics, coatings, and batteries.

Asia Pacific accounted for about 58 percent of global market share in 2024 and is expected to remain the largest and fastest-growing regional market, supported by expanding tyre and rubber manufacturing bases in China, India and Southeast Asia. The region’s carbon black market was valued at USD 16.95 billion in 2025 and is projected to reach USD 26 billion by 2034.

“The Asia Pacific region continues to lead both in production and consumption of carbon black, owing to its strong automotive, tyre and plastics industries,” the report noted, adding that China remains the world’s largest producer and consumer.

The furnace black segment dominated the market in 2024, accounting for about 60 percent of global industry share, due to its superior reinforcing properties in tyres and versatility in plastics and coatings. Meanwhile, the tyres and rubber products segment held a 55 percent share, reflecting the material’s indispensable role in the automotive sector.

Performance applications such as batteries, conductive polymers, and specialty coatings are emerging as key growth drivers. Demand for specialty carbon black and conductive grades is rising with the proliferation of electric vehicles, renewable energy systems, and electronics manufacturing.

Artificial intelligence (AI) is also shaping the carbon black industry, with automation and predictive analytics enhancing process efficiency, product consistency, and sustainability, the report said. AI-driven systems are enabling real-time monitoring and predictive maintenance in production plants, reducing waste and energy consumption.

Sustainability remains a key trend, with manufacturers investing in greener technologies, renewable feedstocks and recovered carbon black (rCB) from recycled tyres to meet circular economy goals. “Turning end-of-life tyres and rubber waste into recycled carbon black is opening new sustainable pathways for producers,” the study noted.

Among key players profiled in the report are Tokai Carbon Co., Ltd., Continental Carbon, Jiangsu C-Chem Co., Ltd., Himadri Speciality Chemical Ltd., Sid Richardson Carbon & Energy Company, Cancarb Limited, Philips Carbon Black Ltd., OCI Company Ltd., Columbian Chemicals Co. (Birla Carbon), Aditya Birla Group, and Raven SR, LLC.

Recent industry developments include PCBL Chemical Ltd.’s establishment of a wholly owned US subsidiary in Delaware in July 2025 to enhance supply chain localisation and strengthen its North American footprint, as well as the West Bengal government’s efforts to attract foreign investment in its carbon black industry to support the electric vehicle, tyre, and battery markets.

The report also forecasts rapid growth in North America, fuelled by clean manufacturing practices, sustainable process adoption and expansion in high-performance plastics and battery applications. Europe, meanwhile, is benefiting from stricter environmental regulations and the EU Green Deal, which are promoting eco-friendly and specialty grades.

The global carbon black market is expected to maintain steady long-term growth as manufacturers diversify into advanced applications and invest in sustainable production technologies to meet evolving industrial and environmental demands.

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Kraton Corporation, a leading global producer of speciality polymers and high-value biobased products derived from pine chemicals, has revealed a new strategic initiative for its Berre, France facility. The plan involves streamlining its polymer operations to concentrate exclusively on manufacturing USBC products, which will result in the cessation of HSBC production at that site.

This move is designed to bolster Kraton's long-term competitiveness by optimising its manufacturing footprint in reaction to a global overcapacity for HSBC. The company has formally started an information and consultation process with the local Works Councils, with a final decision expected following this mandatory period. The company has reaffirmed its commitment to supplying HSBC from its broader global network and to leveraging its worldwide presence to continue adapting to market demands.

Prakash Kolluri, President, Kraton Polymers, said, “Our aim with this plan is to strengthen Kraton’s long-term competitive position by optimising our manufacturing footprint in response to changing market dynamics associated with global overcapacity of HSBC production capability. With this step, we are preparing Kraton for a sustainable future by securing Kraton’s position as the leading global HSBC producer. Kraton is fully committed to supporting our customers through this transition with supply of HSBC products produced within our unmatched global manufacturing network. We recognise the impact of these actions, and are committed to a safe, respectful and supportive transition. The health, safety and well-being of the employees remain our top priorities.”

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Continental is accelerating its transition towards a circular economy by systematically increasing the use of renewable and recycled materials in its tyres. The company, which averaged a 26 percent sustainable material share in 2024, has set an ambitious target to raise this to at least 40 percent within five years. This strategy involves not only internal innovation but also actively encouraging its supply chain to develop and provide more sustainable raw materials.

A critical area of development is finding green alternatives for reinforcement materials like steel and textiles, which are essential for tyre safety, durability and performance. These materials can constitute over 18 percent of a passenger car tyre, and even more in commercial vehicle tyres. Continental is already integrating recycled steel and is pioneering the use of polyester yarn made from recycled PET bottles. Depending on the tyre size, the carcass of a single passenger car tyre can incorporate the equivalent of up to 15 bottles. This recycled polyester, developed with partner OTIZ, is verified to cut CO₂ emissions by approximately 28 percent compared to conventional materials and is already featured in production tyres like the UltraContact NXT.

The company's sustainable material portfolio extends beyond reinforcements. It includes synthetic rubber derived from used cooking oil, bio-based resins from waste streams and silica obtained from rice husk ash. Complementing these material advances is a commitment to greener manufacturing processes. Together with Kordsa, Continental has developed COKOON, an adhesion technology that bonds textiles to rubber without harmful chemicals. In a move to uplift the entire industry, this innovative solution has been made available to all tyre manufacturers as a free, open-source license, demonstrating Continental's broader commitment to fostering industry-wide sustainability.

Dr Matthias Haufe, Head of Material Development and Industrialization, Continental Tires, said, “We are not reinventing the wheel – but we are reinventing the tyre, with more sustainable materials and more environmentally compatible production processes. It’s not just about the rubber itself. We also focus on the materials that give the rubber its shape and make tyres stable and safe. Recycled steel and polyester yarn made from recycled PET bottles are important for more sustainable tyre production. Our goal is to use at least 40 percent renewable and recycled materials in our tyres within five years. Every alternative material brings us an important step closer to this goal. When it comes to sustainability, it’s not just the materials we switch to, but also those we deliberately do without.”

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