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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The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly NR Statistical Report for October 2025, providing an overview of key developments in the global natural rubber sector.

According to the report, the global natural rubber market in October was characterised by a distinct bearish trend in pricing. This decline can primarily due to a significant surge in production and export activities, which were initially stimulated by the higher prices seen earlier in the year. Meanwhile, overall demand has remained relatively subdued.

Looking ahead to the full year, projections indicate a modest 1.3 percent increase in global production for 2025, a figure that follows a recent downward revision for Indonesia. On the demand side, consumption is anticipated to grow by a slight 0.8 percent, influenced by an upward adjustment to Indonesia's consumption data. Despite the current price pressures, market sentiment shows some mixed signs of improvement, particularly within the tyre trade of certain specific markets.

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DuPont commenced construction on a new MOLYKOTE speciality lubricants production facility in Zhangjiagang, Jiangsu Province, East China, on 18 November 2025 with a groundbreaking ceremony that was attended by Senior DuPont leadership from the MOLYKOTE business and the Asia-Pacific region, alongside government officials and key customers. This strategic investment, situated within the Yangtze River International Chemical Industrial Park, is projected to be fully operational by the beginning of 2027. The initiative is a key component of the brand's global expansion, designed to significantly enhance its responsiveness to regional market needs and foster local innovation.

The new plant will primarily focus on meeting the robust and growing demand for advanced lubricant solutions across several critical sectors in China, including transportation, industrial manufacturing, energy and electronics. By establishing a local manufacturing presence, DuPont aims to create a dynamic platform for collaboration with regional customers. This will enable the company to deliver next-generation lubricants with greater speed, precision and agility, ultimately shortening lead times and strengthening supply chains.

The MOLYKOTE brand, with a legacy spanning over 75 years, is globally recognised for its expertise in solving complex lubrication challenges and improving energy efficiency. Its comprehensive product portfolio, which includes greases, oils, anti-friction coatings and pastes, serves the automotive and industrial maintenance, repair and overhaul markets worldwide. Supported by a global network of manufacturing and research facilities, the brand continues to build on its reputation for performance and reliability.

Eugenio Toccalino, Vice President and General Manager, DuPont MOLYKOTE, said, “Today’s groundbreaking is the beginning of a new chapter in our journey to better serve our customers in China, innovate faster and to be a partner of choice for solving wear and friction challenges across industries. This facility will boost local capabilities for application and new formulation development, empowering customer collaboration and response in real time.”

Yi Zhang, Global VP and Regional President, DuPont Asia Pacific, said, “We are thrilled to be breaking ground on the MOLYKOTE China production facility in Zhangjiagang. This manufacturing unit will enable us to address current needs and future trends for speciality lubricants. It reflects our confidence in the long-term potential of customers in China and Asia-Pacific region and reinforces our commitment to deliver faster, more resilient and locally tailored solutions.”

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In a significant move to formalise and advance its environmental strategy, Bekaert has launched 'inhera., a new sustainability label. This initiative underscores the company's dedication to a net-zero future by identifying its most impactful innovations that help industrial customers decarbonise more rapidly. The label serves as a mark of performance and trust, spotlighting solutions that meet stringent, externally validated criteria aligned with frameworks such as the EU Taxonomy Regulation.

The core purpose of inhera is to provide clarity and assurance, demonstrating how specific Bekaert products enable tangible progress in reducing carbon emissions, enhancing resource efficiency and promoting circular economic models. This is increasingly critical in a business landscape where demonstrable sustainability is a strategic necessity rather than an optional consideration. The label currently features a curated selection of eight high-performing solutions across sectors like construction, energy and automotive.

These labelled innovations illustrate a practical path toward cleaner industrial processes. For instance, Ampact magnet wire for electric motors cuts direct CO₂ emissions by 10 percent, while Flexisteel hoist ropes for elevators can reduce daily energy consumption by up to 36 percent. Other products, such as Elyta Ultra tyre reinforcements, deliver significant CO₂ savings per tyre and support circular reuse. Material efficiency is another key focus, exemplified by high tensile steel cores for power lines that use over 30 percent less steel and a next-generation Hose Wire that requires 28 percent less wire. Further offerings, including Bezinal Vineyard Plus and subsea cable armouring wire, utilise low-carbon materials and recycled content to achieve CO₂ reductions exceeding 50 percent.

The name 'inhera' was chosen to reflect the company's belief that sustainability is an inherent component of its corporate identity, deeply embedded within its innovation processes and overall mindset. Bekaert positions the label as more than a certification; it represents a partnership with customers to create measurable environmental impact. Ann-Françoise Versele, VP Sustainability, explained, “Sustainability is inherent in everything we do at Bekaert. Through our products and processes, we aim to leave a legacy of sustainability for future generations. Our partners who choose inhera solutions are choosing to accelerate sustainability and create real impact.”

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Nynas has played a pivotal role in a landmark achievement for Croatia's energy sector by supplying its advanced NYTRO BIO 300X insulating liquid. This fully renewable fluid has been used for the first time in the Croatian market to fill a 630 kVA distribution transformer. The unit, manufactured by KONČAR – Distribution & Special Transformers, was recently installed in Zagreb for HEP ODS, the national Distribution System Operator.

This collaboration marks the inaugural deployment of a ‘Green Transformer’ in Croatia, representing a significant advancement for the country's distribution network. The project underscores a unified drive towards greater sustainability and a reduced environmental footprint for critical power infrastructure. For Nynas, this milestone highlights the practical application and reliability of its bio-based product portfolio.

NYTRO BIO 300X is engineered to provide a drop-in solution that combines high oxidation stability and superior cooling performance, allowing operators to enhance their ecological standards without compromising on operational reliability or transformer longevity. The successful installation stands as a testament to how industry partnerships are actively accelerating the transition to a more sustainable energy future.

Ivanka Radić, responsible for transformer oils at KONČAR - D&ST, said, “The thermal and dielectric tests on the transformer filled with NYTRO BIO 300X were successfully completed, and the unit is now fully operational. As expected, all test results were within the required limits, confirming the reliability and stability of this innovative fluid.”

Daniele Frustagli, General Manager Italy & the Balkans at Nynas, said, “We are very proud to have been entrusted with this project by KONČAR - D&ST and HEP ODS Zagreb, allowing us to showcase to them and the entire electrical industry the advantages of this fully renewable, bio-based hydrocarbon liquid. In addition to meeting and exceeding the IEC 60296 ed. 5 (2020) specification, the product is readily biodegradable, fully bio-based and has ultra-low viscosity.”

Vanja Burul, President of the Management Board at KONČAR - D&ST, said, “This project reflects our ongoing efforts to explore more sustainable insulating fluids. We see great potential for further use of NYTRO BIO 300X in future applications.”

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