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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HS HYOSUNG ADVANCED MATERIALS made a significant impact at InLEX KOREA 2026, the international defence exhibition hosted from 9 to 11 June at the Daejeon Convention Center. The company placed its advanced material technologies at the forefront, positioning them as future cornerstones of the defence industry.

The exhibition, organised by the Ministry of National Defense and the Army Headquarters, gathered military and civilian stakeholders to chart the sector’s trajectory. HS HYOSUNG ADVANCED MATERIALS used the platform to unveil defence applications of its proprietary carbon fibre, aramid and lyocell while actively building customer networks and hunting for global defence contracts.

Three specialised units collaborated on the ground. The Carbon Materials PU featured aerospace-grade propulsion tanks for drones and satellites alongside chopped fibre and 3K carbon fabrics. Concurrently, the Aramid PU presented ballistic helmets and body armour woven from heat-resistant, high-strength aramid yarns aimed at maximising soldier safety.

In a separate showcase, the Tire Reinforcement Materials PU introduced eco-friendly lyocell yarn and carbonised lyocell fabrics. The Aramid PU’s protective gear and the Carbon Materials PU’s lightweight composites collectively demonstrated how HS HYOSUNG ADVANCED MATERIALS is broadening the use of advanced composites in military applications.

Lim Jin Dal, Chief Executive Officer of HS HYOSUNG ADVANCED MATERIALS, said, “Through this exhibition, we hope to demonstrate how our advanced high-performance materials technologies can be applied to Korea’s defence industry. Building on our continuous R&D efforts and commitment to localising advanced materials, we will contribute to establishing a stable supply chain and continue growing together with the defence industry.”

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ARLANXEO and Covestro have deepened their partnership to enhance sustainability in synthetic rubber manufacturing. ARLANXEO has incorporated ISCC PLUS-certified chlorine from Covestro into its chloroprene rubber production, resulting in a marked decrease in the product environmental footprint of the Baypren portfolio. Covestro produces this certified chlorine using renewable electricity, thereby supporting lower greenhouse gas emissions across the supply chain.

Beginning in January 2026, ARLANXEO’s entire chloroprene rubber output relies exclusively on ISCC PLUS-certified chlorine, representing a major advancement in the company’s long-term sustainability strategy. Depending on the product grade, this shift delivers an average 20 percent reduction in global warming potential compared to 2025 levels. As a critical raw material provider, Covestro has enabled this transition by ensuring a steady supply of the certified chlorine.

The adoption of ISCC PLUS-certified feedstocks strengthens ARLANXEO’s standing as a premier supplier of sustainable elastomer solutions for industries with aggressive climate goals, including automotive, construction, industrial manufacturing and adhesives. Additionally, ARLANXEO now offers Baypren Eco grades that combine certified chlorine with ISCC PLUS-certified butadiene.

These eco grades allow for even deeper environmental impact reductions while maintaining full performance, helping customers meet their own sustainability targets without compromising product quality.

Niels van der Aar, Head of Sustainability at ARLANXEO, said, “Integrating ISCC PLUS-certified materials into our production is a key step in reducing the environmental footprint of our CR products. It underlines our commitment to supporting customers with more sustainable material solutions while advancing transparency along the value chain by supplying corresponding product environmental footprint data for ARLANXEO’s entire CR product portfolio.”

Moritz Winterstein, Head of Trading Cluster Basic Chemicals EMEA at Covestro, said, “At Covestro, we support our customers in reducing emissions along the value chain by supplying more sustainable basic chemical raw materials from our multiple ISCC PLUS-certified production sites. Our collaboration with ARLANXEO demonstrates how certified raw materials and renewable electricity can contribute to lowering the product environmental footprint of downstream applications and support customers in achieving their sustainability targets.”

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The Association of Natural Rubber Producing Countries (ANRPC) released its April 2026 report, highlighting rising prices despite lower production. Output fell 2.59 percent year-on-year due to the seasonal wintering period, dry weather across South and Southeast Asia and El Niño concerns. Brent crude surged to USD 117.29 per barrel, up 13.72 percent from March, driven by Middle East disruptions, which boosted centrifuged latex valuations.

Physical prices rose across all major grades. SMR-20 in Kuala Lumpur increased 4.61 percent to USD 2.13 per kilogramme, while STR-20 in Bangkok climbed 3.53 percent to USD 2.27. RSS-3 in Bangkok jumped 8.10 percent to USD 2.77, and RSS-4 in Kottayam rose 6.53 percent to USD 2.50. Centrifuged latex in Kuala Lumpur gained 12.47 percent to USD 1.93 per kilogramme. Futures markets remained firm, with the Shanghai Futures Exchange September 2026 contract averaging CNY 17,009 per tonne.

For 2026, global production is projected at 15.322 million tonnes, up 2.2 percent, with upward revisions for China and Malaysia. Consumption is forecast to grow 1.3 percent to 15.550 million tonnes, driven by electric vehicle production and recovery in rubber goods. In April alone, estimated output was 772,000 tonnes, while consumption reached 1,235,000 tonnes, a 2.3 percent annual rise.

Trade patterns diverged sharply. China’s imports fell 13.35 percent to 538,200 tonnes due to high inventories, while India’s imports surged 38.79 percent on strong manufacturing demand. Thailand’s exports contracted 4.28 percent to 378,000 tonnes, but Cambodia’s exports soared 106.49 percent. The Malaysian ringgit strengthened to near 3.96 against the US dollar, while the Thai baht stabilised around 3.07 after volatile trading.

The macroeconomic environment remained tense, with US-China trade friction, the Middle East conflict and the US Federal Reserve holding interest rates at 3.50 to 3.75 percent. The near-term outlook for natural rubber is cautiously positive but subject to heightened volatility.

The ANRPC reaffirmed its commitment to objective analysis for the sustainable development of the natural rubber sector. Member governments and stakeholders were encouraged to use the report’s findings for evidence-based policies.

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Indorama Advanced Oxides, a subsidiary of Indorama Corporation, has successfully restarted production at Huelva facility in Spain, achieving its first tonne of Titanium Dioxide (TiO₂) output. The plant, which has an annual capacity of 80,000 tonnes, represents the company’s strategic entry into the global titanium dioxide market. This milestone follows Indorama’s recent completion of the site acquisition from Venator P&A Spain.

The restart marks a crucial step in returning the facility to full operation after the acquisition, ensuring continued supply of the essential white pigment to customers across Europe and global markets. The Huelva team demonstrated strong collaboration and safe execution in resuming activities. This white pigment remains critical for the European paints, coatings and plastics industries.

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