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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Birla Carbon is set to participate in the upcoming Tire Technology Expo 2026, scheduled to take place in Hannover, Germany, from 3 to 5 March 2026. Attendees can find the company at Stand C 224, where it will present its latest innovations in carbon black and sustainable materials. The focus will be on solutions specifically designed to meet the evolving demands of the tyre industry, particularly in enhancing performance while aligning with broader environmental objectives.

The exhibition will serve as a platform to demonstrate how Birla Carbon’s advanced materials contribute to greater tyre durability and fuel efficiency. These developments are especially pertinent for next-generation mobility, including the specific requirements of electric vehicles. The company aims to show tire manufacturers how performance enhancements can be achieved without sacrificing sustainability commitments.

A key theme of their presence will be the strength and agility of their supply network across the EMEA region. By emphasising its robust local manufacturing and distribution framework, Birla Carbon intends to highlight its role as a dependable innovation partner. This infrastructure is built to ensure consistent quality and supply chain resilience, allowing for effective collaboration even in fluctuating market conditions.

Sustainability will be woven throughout the company’s engagement at the expo. Birla Carbon plans to detail its journey towards achieving net zero carbon emissions, spotlighting advancements like its Continua Sustainable Carbonaceous Material (SCM). The widespread ISCC Plus certification across its global manufacturing sites will also be featured, underscoring its commitment to traceable and responsible sourcing practices throughout the value chain.

John Davidson, Chief Sales, Marketing & Sustainability Officer, Birla Carbon, said, “Birla Carbon brings a range of innovative carbon black solutions, backed by its decades of manufacturing leadership, at a time when the industry is focused on maximising tyre performance across diverse mobility requirements. As mobility evolves towards electric and more energy-efficient platforms, carbon black is increasingly becoming a key performance enabler, directly influencing durability, rolling resistance and lifecycle emissions. Tire Technology Expo provides an impactful global platform to demonstrate how our advanced carbon material solutions are engineered for modern mobility and sustainability.”

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Sri Trang Agro-Industry Public Company Limited (STA) is advancing Thailand’s agricultural digital transformation through its homegrown platform, the Sri Trang Friends application. Launched in 2019 with the vision of providing a comprehensive digital tool for rubber farmers, the platform has since evolved to serve a broader agricultural community, including palm growers. It is designed to streamline access to information, services and various support mechanisms, creating a direct link between the company, farmers and supply chain participants.

A key recent development is the introduction of the Friends Shop feature and the Friends Point rewards system. This enhancement integrates local merchants from communities nationwide into the application, allowing farmers to conduct convenient transactions while helping to lower their daily expenses. The points accumulated can be used as cash equivalents or exchanged for a wide range of benefits, including essential goods and services, thereby stimulating local economic activity. The platform’s utility has also been extended to Sri Trang Group employees and the general public, who can now earn and redeem points for discounts or payments at participating outlets such as supermarkets, fuel stations and coffee shops. This expansion ensures the app delivers practical, lifestyle-oriented advantages to a wider user base.

According to Executive Director Vitchaphol Sincharoenkul, the application was originally conceived under the concept of ‘One App, Complete Services for Rubber Farmers’ to strengthen farmer engagement, improve coordination efficiency and ensure fully traceable and transparent produce trading. Beyond these operational goals, it also opens new marketing channels for local communities and fosters deeper collaboration across the agricultural value chain. The company is actively broadening its network of partners to diversify the benefits and merchant options available to users.

Currently, the Sri Trang Friends platform has attracted over 150,000 registered users, with more than 40 community merchants across various regions either already onboard or preparing to join. This growth underscores the company’s commitment to leveraging a Thai-developed digital solution to empower modern farmers, reinforce local economies and drive sustainable long-term progress within the nation’s agricultural sector.

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Himadri Speciality Chemical Ltd (HSCL) has officially launched commercial production at its new 70,000 metric tonne per annum speciality carbon black line in Mahistikry, West Bengal. This brownfield expansion elevates the company’s total carbon black manufacturing capacity to 250,000 MTPA, with 130,000 MTPA specifically dedicated to speciality grades at this single location. As a result, the Mahistikry facility now holds the distinction of being the largest site in the world for speciality carbon black production.

The development represents a pivotal achievement in the company’s strategic roadmap, solidifying its global standing in the advanced materials sector. By significantly increasing its speciality portfolio, the company is better positioned to meet the rigorous demands of high-value industries such as plastics, inks, paints and coatings. The project integrates cutting-edge process technology with stringent quality controls and energy-efficient systems, ensuring that premium-grade products are consistently delivered to an international client base.

Financially, the new capacity is set to positively influence revenue streams and bolster margins over the coming years. The expanded scale not only enhances operational efficiency and supply chain dependability but also accelerates the company’s ability to innovate and respond to market shifts. As worldwide demand increasingly favours tailored, high-performance carbon solutions, this enhanced infrastructure provides a distinct competitive edge through improved agility and product development capabilities.

Anurag Choudhary, CMD & CEO, Himadri Speciality Chemical Ltd, said, “The commencement of commercial operations of our 70,000 MTPA Speciality Carbon Black line at Mahistikry marks the beginning of the next phase of growth in our advanced carbon materials journey. With this expansion, Mahistikry becomes the world’s largest single-location Speciality Carbon Black facility, with a capacity of 130,000 MTPA. This milestone significantly enhances our production capabilities and positions us strongly to capture rising global demand in premium, application-specific segments such as plastics, inks, paints, coatings and other specialised industries. We remain committed to disciplined expansion, operational excellence, sustainability and delivering high-performance solutions that create long-term value for all stakeholders.”

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Solvay has announced that it will optimise the soda ash production capacity at its Torrelavega site in Spain from 600 kilotonnes to 420 kilotonnes, effective from the third quarter of 2026 and pending the required consultation process. This decision is a direct response to ongoing global oversupply and persistently high energy and carbon costs in Europe.

By optimising its operational level, the company aims to strengthen the long-term competitiveness and sustainability of its remaining production at the facility. The Torrelavega site will continue to serve regional customers by focusing on soda ash and premium sodium bicarbonate, with supply guaranteed through both local operations and Solvay’s global network. Importantly, sodium bicarbonate production will remain unaffected.

This adjustment also supports the company’s commitment to the energy transition, including a major biomass initiative designed to significantly reduce coal usage at the site. As a result of the capacity reduction, a net decrease of up to 77 positions is expected. Solvay is committed to managing this transition responsibly and will engage closely with employee representatives to develop socially supportive solutions and measures for those impacted.

Etienne Galan, President of Solvay Soda Ash & Derivatives, said, “Solvay is taking decisive steps to enhance the competitiveness and sustainability of its soda ash operations. Soda ash is critical for essential applications, and Solvay remains firmly committed to the business. We are strategically investing now to cement our competitiveness for decades to come, including the deployment of carbon neutral soda ash processes as part of our energy transition roadmap. At the same time, we urgently need the regulatory framework to align with our industrial reality and the investments that are needed for this transformation.”

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