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.

Japan's Kuraray Co Ltd reported a 42 percent plunge in first-half operating profit as its rubber and speciality chemicals business grappled with weakened European demand and inventory valuation losses, prompting the company to slash its full-year earnings forecast.

The Okayama-based manufacturer, known for its synthetic rubber and speciality polymers used in automotive and industrial applications, posted operating income of 26.3 billion yen for the six months ended June 30, down from 45.5 billion yen a year earlier.

Net sales slipped 2.7 percent to 400.0 billion yen, with the company's flagship vinyl acetate segment - which includes rubber-related products - bearing the brunt of the downturn as volumes declined across key markets.

"Sales volume did not increase as much as expected due to the European economic stagnation and other factors, and overall segment income decreased due to the negative impact of inventory valuation differences and higher raw material and fuel prices," the company said in its earnings statement.

The vinyl acetate division, Kuraray's largest revenue contributor, saw operating income tumble 31.9 percent to 29.9 billion yen despite maintaining sales of 202.9 billion yen. The segment includes the company's EVAL barrier resins used in food packaging and automotive fuel tanks, as well as polyvinyl alcohol (PVOH) resins with rubber-like properties for industrial applications.

Kuraray's isoprene chemicals and elastomers business, which produces synthetic rubber compounds, showed signs of recovery with operating losses narrowing to 1.3 billion yen from 4.0 billion yen a year earlier. Sales volumes increased as demand remained firm, particularly in Europe and the United States, whilst operations at the company's Thai manufacturing base stabilised.

However, the broader economic malaise weighed heavily on performance. Rising natural gas costs in the US and Europe - key raw materials for rubber production - further squeezed margins. US natural gas prices averaged USD 3.69 per MMBtu compared with USD 2.21 a year earlier, whilst European gas costs climbed to 41 euros per MWh from 30 euros.

The disappointing first-half results prompted Kuraray to revise down its full-year operating income forecast to 75.0 billion yen from an earlier projection of 90.0 billion yen, though it maintained its annual dividend at 54 yen per share.

Chief Financial Officer Hitoshi Kawamura highlighted inventory valuation differences as a significant drag on earnings, particularly affecting the company's rubber and polymer segments, where raw material price volatility has been pronounced.

Looking ahead, Kuraray expects second-half performance to improve, with operating income projected at 48.7 billion yen compared with 26.3 billion yen in the first half. The company is banking on a gradual recovery in European demand and the benefits of recent capacity optimisations.

The firm is also pursuing strategic shifts in its portfolio, including plans to expand its optical-use PVOH film production line and the acquisition of US-based Nelumbo Inc, whilst discontinuing production of certain acrylic polymers and polyester-related products.

French biotech firm expands into industrial fabrics market through enzymatic PET recycling technology

French biotechnology company CARBIOS has signed a multi-year commercial agreement with Thailand's Indorama Ventures to supply recycled materials for tyre manufacturing, marking the firm's expansion into the industrial fabrics sector.

Under the deal, CARBIOS will provide biorecycled monomers from its planned Longlaville industrial plant to Indorama Ventures, the world's largest polyester producer. The Thai company will transform these materials into recycled polyethylene terephthalate (r-PET) filaments for use in tyre reinforcement by French tyre manufacturer Michelin.

The partnership represents CARBIOS's entry into a new market segment beyond its existing focus on cosmetic packaging applications. The company uses proprietary enzymatic recycling technology to break down complex PET waste into high-quality recycled materials.

"This commercial agreement with Indorama Ventures marks a new step in the realisation of our industrial project," said Vincent Kamel, chief executive of CARBIOS. "It confirms the trust of Indorama Ventures and Michelin in our PET biorecycling technology."

The deal comes weeks after CARBIOS signed its first sales contracts for biorecycled PET with two unnamed global cosmetics companies, as the firm builds momentum ahead of the commercial launch of its Longlaville facility.

Michelin, which has committed to using 100 percent renewable and recycled materials by 2050, said the partnership advances its circular economy objectives.

"This partnership is a tangible expression of our commitment to turning complex waste into high-performance materials," said Fabien Gaboriaud, director of circularity and renewable & recycled materials at Michelin Group. "By integrating enzymatically recycled r-PET into our tyres, we are marking a new milestone on our journey toward achieving 100 percent renewable and recycled materials by 2050."

Indorama Ventures, which generated $15.4 billion in revenue last year, said the alliance underscores its commitment to circular economy principles. The company employs approximately 25,000 people across manufacturing operations in Europe, Africa, the Americas, and Asia Pacific.

"This alliance with both, CARBIOS and Michelin, underlines our commitment to plan ahead and take a leading role in shifting the industry towards circularity," said Renato Boaventura, global market head mobility at Indorama Ventures.

CARBIOS, founded in 2011, has developed enzyme-based biological processes to break down plastics as part of efforts to prevent plastic pollution and accelerate the transition to a circular economy. The company operates an industrial demonstration plant for biorecycling that has been operational since 2021.

Construction of what the company describes as the world's first biorecycling plant is expected to resume in the second half of 2025, subject to securing additional funding.

Cabot Corporation has launched LITX 95F, a high-performance conductive carbon additive designed for lithium-ion batteries in energy storage systems (ESS). Optimised for residential, commercial and industrial ESS applications, this advanced material enhances conductivity, extends cycle life and improves processability – critical for systems requiring durability under frequent charging and discharging.

With the global ESS market expanding due to renewable energy adoption and demand for grid stability, battery manufacturers need cost-effective, high-performance solutions. LITX 95F meets these needs by boosting energy density and cycle life while maintaining stability. Pouch cell tests with thick electrodes confirm its superior capacity retention, offering manufacturers greater flexibility in ESS design.

The material’s high-structure morphology strengthens conductivity and stability over repeated cycles. Additionally, its compatibility with thick cathode designs helps lower material costs without sacrificing performance. This innovation supports the growing ESS sector by enabling more efficient, reliable and scalable battery solutions.

Jeff Zhu, Executive Vice President and President, Carbon & Silica Technologies, Battery Materials and Asia Pacific Region, said, “As the global energy landscape continues to evolve, the ESS market requires advanced materials that deliver both performance and efficiency. Our new LITX 95F product is a direct response to the needs of the market and our battery customers – leveraging our deep industry expertise with proven performance to help scale ESS applications faster and more efficiently. This launch reflects our commitment to enabling a more sustainable future by delivering innovative solutions for battery technologies that support the energy transition at a global scale.”

The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly NR Statistical Report for June 2025, providing an overview of key developments in the global natural rubber sector. The latest data indicates a sustained downward price trend, primarily driven by improving supply conditions in major producing nations, elevated stockpiles at key ports and ongoing trade policy uncertainties.

Market analysts attribute the bearish sentiment to a combination of factors, including increased output from leading rubber-producing countries and subdued industrial demand, particularly from tyre manufacturers. These conditions have contributed to mounting pressure on prices, with limited signs of immediate recovery. The ANRPC notes that while production levels remain stable, cautious demand projections persist due to broader macroeconomic concerns, including potential trade disruptions and slowing global economic growth.

Projections for 2025 suggest a modest 0.5 percent increase in worldwide natural rubber production compared to the previous year. Meanwhile, consumption is anticipated to grow by 1.3 percent, reflecting a slight but uneven recovery across key markets. However, analysts warn that external factors, such as shifting US tariff policies and weaker-than-expected industrial activity, could further dampen demand growth in the coming months.