Polymer producers have responded to the changing tyre industry expectations, their innovations take into account a more reactive functionality within polymer architecture, and this is closely matched by increasingly greater degrees of filler surface chemistry. As a result, tyre compound properties may now be tailored to meet quite specific tyre performance targets.

Tyre processing methods also underwent progressive stages of modernisation in recent years, for example, more sophisticated reactive mixing technology together with high-speed extrusion systems allowing for direct extrusion onto the building drum become established as cost effective production routes for many of the major producers.

These advancements however bring about their own conflicts, processing pathways involving multiple stages, often with the ability to rework compound or adjust rheological properties by additional time or energy input during the process are no longer viable options for most tyre producers. It has thus become necessary to achieve processability through an increasingly narrow operating window.

Formulations optimised to achieve peak tyre performance in most cases also tend towards more challenging processing characteristics. This is to be expected; the use of high and narrow molecular weight reactive polymers alongside fillers having high surface area and chemistry, often in loadings above that of the polymer are the norm. The trend towards usage of high loading of plasticiser and resinous materials to adjust tyre tread grip and traction response all contribute to a less forgiving processing nature. Often those compounds that are highly reinforced appear the most fragile during processing and poor green strength with an easily tearing or crumbly compound appearance are often-discussed processability issues. By contrast, the use of high loadings of resins and plasticisers, for example in winter or high-performance tyre formulations, results in compounds that during processing can more resemble chewing gum than tyre treads!

The use of process additive chemicals in an attempt to overcome the processing limitations observed gives rise to further conflicts; Lubricant additives might improve compound surface appearance; however, green strength will probably further reduce due to the unwanted softening effect. The same is true for release additives where lower tack unfortunately remains at a higher value than the also lowered tensile strength of the compound. Filler dispersion is often targeted by additives, however higher loading of fillers mandate equally higher additive loadings, we should more accurately discuss loading as “parts per hundred of filler” not rubber, and under the appropriately higher additive loading, the risk of interference with vulcanisation properties or even additive migration leading to surface bloom become realistic concerns.

Conflicting performance characteristics

The development team at Schill + Seilacher has recognised the need to decouple conflicting performance characteristics found within conventional process additive chemistries. As a result, innovation within our Struktol® range offers tyre compounders opportunities to achieve processability without compromise.

Reduced viscosity leading to better extruder flow properties and improved surface appearance, whilst at the same time achieving an increased compound green strength can be realised by use of Struktol HT 300, a new generation of reactive process additive.

An extract of key processing and property influence in a typical highly silica filled sSBR tread compound are highlighted in the following data.

Significantly lowered Mooney viscosity as well as better mixer batch off with reduced sticking to the mixer rotor and gate with Struktol HT 300 are observed.

An increase in compound green strength was obtained by the addition of Struktol HT 300; this is the opposite of expectation for conventional process additive chemistry, where reduced viscosity is obtained. In addition, the filler dispersion as evidenced by a reduction in the so-called “Payne Effect” as tested in uncured compound by means of RPA strain sweep, is also improved.

Lab extrusion trials, using cold feed extruder demonstrate improved surface appearance and lower compound pressure achieved by use of Struktol HT 300, both desirable processing conditions.      

Physical properties are also acceptable, with a progressive increase in tensile strength an elongation and maintenance of stiffness with loading of 6 phr of process additive, only at higher loading of 12 phr would a balancing slight reduction in process oil be required.

Compound hardness remained unchanged alongside improved wear resistance, as measured by DIN abrasion loss testing, even when using higher loading of process additive, are important aspects.

The ability to decouple the relationship between lubrication, important for improved rheological behaviour, and the maintenance of strength and stiffness in both the uncured and vulcanised condition is only possible with such new and innovative class of process additive. This departure from conventional thinking offers the tyre compounder significant degree of freedom to retain the benefits in terms of easier processability without sacrifice of key tyre performance properties.

In this example, the use of Struktol HT 300 prioritised green strength alongside reduced viscosity. By contrast, our new Struktol HT 250 decouples release from other properties, especially effective for winter tyre tread; compound stickiness is resolved without compromise of viscoelasticity.

Ensuring that migration and ultimately bloom within rubber compounds is kept to the lowest level is important for final article aesthetics, for tyres additional considerations arise; they are composite structures, therefore it is imperative that chemicals do not migrate across boundary layers in an uncontrolled manner, which could result in changed behaviour or interfacial adhesion failure over time. In order to limit migration, the compatibility, solubility and concentration of chemicals are carefully considered. However, one method of ensuring long-term stability involves chemically binding the additive within the vulcanisation network.

At Schill + Seilacher, we have achieved this degree of crosslinking capability for a number of new-generation Struktol process additives. Their usage allows the compounder to avoid completely the risk of migration and bloom due to additive presence.

Photographs of two vulcanised rubber sheets based on the same formulation. On the left-hand side, evidence of typical surface bloom, which may occur due to migration of a conventional process additive, on the right, containing reactive additive Struktol HT 600 as replacement, it can be seen that bloom was eliminated.

This technology also opens tremendous opportunities to “fix” process additives in place within the respective component, the role of additives withinthe cross-linking mechanism may additionally lead to vulcanisate performance characteristics.

                                                                                  One interesting tyre related example involves the development of a superior tyre curing bladder performance, here we have developed new reactive plasticisers called Struktol HT 815 and Struktol HT 820, their use is directed towards resin-cured butyl rubber. This combination of polymer and curing system provides for superior heat resistance with excellent flex fatigue resistance and is used as the basis for tyre curing bladders. Here the replacement of widely used castor oil as plasticiser with new Struktol HT 800 series product leads to a significantly improved bladder performance life, with greater stability in viscoelastic properties. Reduced stiffening of the bladder, due to lower degree of plasticiser migration translated into a much lower flex-cracking rate, especially after high temperature steam ageing.

Reactive Struktol plasticisers, HT 815 and HT 820 exhibit a significantly reduced flex cracking rate when compared to the widely used castor oil, which readily migrates from the bladder; as a result, significant extension of bladder service life is possible.

New reactive process additives, with tailored functionality to closely match the specific chemistry of polymers, fillers and cure systems are actively developed. These innovative products under the Struktol brand offer tyre compounders a more comprehensive toolkit in order to tailor compound performance to meet tyre performance demands. The conflicts of property versus processability diminish and new possibilities emerge!

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As Extended Producer Responsibility (EPR) frameworks expand globally, the tyre industry is undergoing a structural transformation. Collection systems are improving, traceability is increasing and investments in recycling technologies are accelerating. However, one critical tension remains insufficiently addressed: the speed of industry evolution is outpacing the agility of public policy. And within that gap, one key question emerges: where does retreading fit in this new circular economy architecture?

A STRUCTURAL PARADOX

Retreading represents one of the most efficient forms of resource optimisation in the tyre lifecycle. It extends product life, reduces raw material consumption and lowers emissions. Yet, in many regulatory frameworks, it is still treated ambiguously – often grouped with recycling rather than recognised as prevention or preparation for reuse. This distinction is not semantic. It is strategic. Because when policy fails to differentiate, markets fail to prioritise.

A FAST-MOVING INDUSTRY, A SLOW-MOVING FRAMEWORK

The tyre market is evolving in real time:

1. Increasing penetration of low-cost imports.
2. Growing variability in product quality.
3. Accelerated turnover cycles.

Retreading, in this context, becomes more than a circular solution. It becomes a filter of industrial quality. Not all tyres are equally retreadable. And that difference defines their real contribution to circularity. Yet most EPR systems continue to operate with uniform economic signals, failing to distinguish between products that enable multiple lifecycles and those that exit the system after a single use.

SIGNALS FROM EUROPE

Recent developments in countries like Portugal – where eco-fees applied to retreaded tyres approach those of low-cost, non-differentiated new tyres – highlight a concerning trend. Similarly, in Spain, industry representatives continue to advocate for a clearer institutional recognition of retreading within EPR systems. These cases illustrate a broader issue: circular policies can unintentionally undermine higher-value circular strategies.

THE MISSING LINK: PERFORMANCE-BASED POLICY

What is missing is not regulation. It is regulatory precision. EPR systems have successfully organised waste flows. But they have not yet evolved to reward performance within the lifecycle. This is where eco-modulation becomes critical.

ECO-MODULATION AS A STRATEGIC LEVER

Eco-modulation should not be a marginal adjustment. It should be a core industrial policy tool. Properly designed, it can:

• Differentiate tyres based on real circular
• performance.
• Incentivise durability and retreadability.
• Penalise short-lifecycle, non-recoverable products.
• Align market behaviour with system objectives.
• To operationalise this, we need new metrics.

FROM COMPLIANCE TO PERFORMANCE: A PROPOSED FRAMEWORK

The next step for EPR systems is to move towards performance-based differentiation. This could be implemented through instruments such as:

• Retreadability Index (RI)
• Performance Score (CPS)

These would measure:

• Number of effective retreading cycles per tyre.
• Structural durability and casing quality.
• Real contribution to lifecycle extension.

Under such a system:

• Tyres with higher retreadability would receive lower eco-fees.
• Products that systematically fail to re-enter the cycle
• would face higher costs.
• This is not just a technical refinement. It is a shift from:
• Generic compliance.
• To intelligent market shaping.

THE LATIN AMERICAN PERSPECTIVE

In Latin America, the stakes are even higher.

The region faces:

• Structural dependence on imported tyres.
• Strong presence of low-cost, low-durability products.
• Emerging EPR frameworks (Chile, Costa Rica, Peru, Ecuador)

Chile, for example, through its EPR law (Ley REP), has made significant progress in structuring collection and recovery targets. However, like many systems, it still faces the challenge of fully integrating reuse strategies into its economic logic. Under these conditions, retreading is not just an environmental solution. It is a strategic industrial capability.

BEYOND WASTE MANAGEMENT

Latin America has a unique opportunity to design EPR systems not only to manage waste

but to govern resources and shape markets.

This means:

• Incentivising retreadable tyres
• Strengthening local retreading industries
• Reducing dependence on short-lifecycle imports
• Building resilience into supply chains

But this requires something critical: policy agility. Because if regulation lags behind market dynamics, it will not transform the system – it will merely formalise its inefficiencies.

A STRATEGIC CONCLUSION

If EPR systems are designed without properly integrating retreading – and without differentiating based on actual circular performance – they risk reinforcing a linear logic under a circular narrative. For emerging regions, this would be a critical mistake

The discussion around repair, reuse and retreading can no longer be treated merely as a waste management issue. It is increasingly becoming a matter of industrial resilience, strategic autonomy and economic security.

As global supply chains face growing pressure from geopolitical fragmentation, logistics disruptions and volatility in raw material markets, extending the useful life of products is emerging as a strategic capability for nations and industries alike.

In this context, Right to Repair should not be understood only as a consumer right but also as an industrial policy tool capable of strengthening local economies, reducing external dependency, preserving technical capabilities and supporting more resilient production systems.

Retreading, remanufacturing and reuse are part of a broader transition where value creation is no longer based exclusively on extraction and disposal but increasingly on intelligence, efficiency and lifecycle management.

CIRCULARITY WITHOUT HIERARCHY BECOMES INEFFICIENCY. REGULATION WITHOUT DIFFERENTIATION BECOMES DISTORTION.

Final note

The future of the tyre industry will not be defined only by how we recycle, but by how intelligently we extend the life of what we already produce. And that requires alignment between:

• Industry dynamics.
• Policy design.
• And strategic vision.

In that equation, retreading must move from the margins to the centre. Because properly understood, it is not just a process. It is a strategic filter, an industrial policy tool and a geopolitical lever.

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The Association of Natural Rubber Producing Countries (ANRPC) has released its market report for May 2026, depicting a sector characterised by sustained price strength and firm fundamentals. The global natural rubber market received additional upward momentum from a decline in Brent crude oil prices, which averaged USD 107.14 per barrel during the month. This represented a month-on-month decrease of 8.65 percent, attributed to easing geopolitical tensions in the Middle East and the temporary reopening of the Strait of Hormuz, which collectively bolstered the commodity's outlook.

Global production projections for 2026 stand at 15.337 million tonnes, marking a 2.4 percent increase from the previous year, with growth driven by Thailand, China, India and Malaysia, even as output moderates in Indonesia and Vietnam. Monthly production, however, fell to 997,000 tonnes in May, a year-on-year decline of 4.7 percent, due to seasonal wintering and dry weather conditions across South and Southeast Asia. Concurrently, worldwide consumption is forecast to rise by 1.3 percent to 15.550 million tonnes for the year, with May's consumption reaching 1.310 million tonnes, a 4.6 percent annual increase. This demand was underpinned by steady tyre manufacturing, electric vehicle-related consumption and resilient purchasing managers' indices in China and India, alongside record auto retail sales in India.

Physical prices for all major grades recorded broad-based gains throughout May, with SMR-20, STR-20, RSS-3, RSS-4 and latex all experiencing increases. Trade flows showed a mixed pattern, as imports from China and India contracted month-on-month, while Malaysia and Vietnam registered significant gains. On the export front, Cambodia, Vietnam and Thailand recorded increases, whereas Indonesia and Malaysia saw declines. Currency movements saw the Malaysian ringgit ease slightly, while the Thai baht traded within a stable range, and both nations reported decelerating GDP growth for the first quarter of 2026. Futures contracts on the SHFE and SGX reflected tightening supply and firm demand, posting notable month-on-month gains.

The market outlook remains cautiously balanced against a backdrop of several macroeconomic factors. Elevated trade tensions between United States and China, ongoing geopolitical conflicts and a steady United States Federal Reserve interest rate policy present potential headwinds. However, these are being offset by supportive elements, including the accelerating adoption of electric vehicles, tight feedstock supply due to adverse weather and the positive market sentiment generated by the European Union's decision to lower anti-dumping duties on Chinese tyres.

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Zeon Corporation has introduced a novel data management system specifically designed for elastomer research and development, marking the company’s first foray into a subscription-based service model. The platform is engineered to centralise and streamline R&D data pertaining to rubber products, with the primary goal of enhancing operational efficiency and accelerating developmental processes for its clientele. The initial phase of the rollout will concentrate on the Japanese market, with a strategic plan to broaden access to other regions in the future.

The elastomer industry frequently grapples with the fragmentation of data across disparate systems, which complicates the effective utilisation of historical information. Through extensive experience in elastomer supply and sustained client engagement, Zeon has identified this operational hurdle as a pervasive issue affecting the entire sector. This recognition has been the catalyst for developing a solution that directly confronts these data management deficiencies.

The newly launched system incorporates specialised functionalities that are finely attuned to the nuances of rubber product R&D. It integrates a comprehensive database that combines master data for key compounding agents available in Japan with extensive catalogue information, facilitating rapid and efficient data access for daily research tasks. The platform’s intuitive interface and user experience are meticulously crafted to optimise usability and data visualisation, with a commitment to ongoing enhancements based on evolving customer requirements.

Zeon has formally designated this data management solution as a growth driver for its strategic initiatives, extending beyond the Phase 3 objectives of its STAGE30 medium-term plan. The company envisions this business becoming a cornerstone of its strategy to augment the value proposition of its elastomer operations. By synergising its deep-seated elastomer expertise with advanced data utilisation technologies, Zeon is poised to foster innovation in client R&D and propel the overall advancement of the elastomer industry.

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A new bio-based cut & chip resin for the most demanding applications.

NaugaShield BIO-TR 30 is SI Group’s latest advancement in bio-based performance resins designed to significantly improve cut and chip resistance in high-severity rubber applications. With approximately 75 percent bio-based content, this innovative material delivers on sustainability targets while exceeding the performance typically associated with petroleum-derived resins, making it a strong choice for applications such as OTR tyres in mining, construction and agriculture, mining conveyor belts, rubber tracks and mill linings.

Cut and chip resistance is a complex set of material behaviours, including static mechanical strength, dynamic response under deformation and ability to withstand sharp impacts and abrasive environments. In demanding applications such as mining or agriculture, materials must tolerate repeated high-strain loading and resist the initiation and propagation of tears. NaugaShield™ BIO-TR 30 was developed precisely to meet these conditions, demonstrating notably low dynamic heat buildup and excellent tear strength – characteristics closely tied to enhanced cut and chip resistance and long-term durability under cyclical loads.

To evaluate its performance, NaugaShield BIO-TR 30 was benchmarked in an Off-road Rib Tread formulation against two widely used industry references: a gum rosin/semi-aromatic C5/C9 resin combination and a styrenated DCPD resin. All materials were tested at an equal loading of 10 phr to provide a direct and unbiased comparison. Under these conditions, the bio-based resin consistently outperformed both alternatives, offering a stronger balance of reinforcing behaviour, improved tear propagation resistance and superior resistance to thermal degradation during dynamic flexing. Further improvements were achievable by reducing the amount of free extender oil in the compound, underscoring the resin’s adaptability in formulation design and its ability to unlock even greater performance when optimised.

These laboratory indicators were corroborated through extended Coesfeld Cut & Chip testing (see chart), in which compounds were subjected to up to 3,000 cycles at 200 rpm under a 200N applied force. Formulations containing NaugaShield BIO-TR 30 exhibited substantially lower mass loss and maintained tread surface integrity more effectively than the hydrocarbon and gum rosin-based-benchmarks. The performance advantage was even more pronounced in compounds adjusted for lower free oil content, confirming that the resin can be tailored to meet the durability requirements of the most challenging operating conditions.

The strong performance of NaugaShield BIO-TR 30 in OTR tread compounds can be readily transferred to other rubber goods that encounter similar wear mechanisms. Applications such as mining belts, agricultural and construction tracks or mill linings benefit from the resin’s ability to reinforce the rubber matrix, reduce crack growth under repeated impact and maintain structural cohesion under high-strain deformation. This versatility allows manufacturers to integrate a 75 percent bio-based resin that supports sustainability by reducing fossil-based content and helping end products last longer while maintaining – and often improving – operational performance across multiple product lines.

NaugaShield BIO-TR 30 is currently available in commercial quantities, enabling compounders and manufacturers to move directly from laboratory evaluation to pilot- and production-scale trials.

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