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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Shin-Etsu Chemical has announced a sweeping price revision for its entire range of silicone products, effective for all shipments from 1 May 2026. The adjustment applies to every product handled by the company’s Silicone Division, with increases set at a minimum of 10 percent. Actual revision rates will vary depending on the specific product category.

The decision follows recent developments in the Middle East, which have triggered sharp surges in crude oil and naphtha prices. This has led to a steep rise in the cost of oil-derived raw materials. Additionally, Shin-Etsu Chemical is confronting higher expenses related to manufacturing energy, product containers, packaging materials and logistics, all of which have contributed to the need for a price correction.

Despite exhausting all possible internal measures to reduce manufacturing costs, the company concluded that these efforts alone cannot absorb the mounting cost pressures. Shin-Etsu Chemical is now committed to fully communicating the situation to its product users and securing their understanding of the necessary selling price revisions.

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The Association of Natural Rubber Producing Countries (ANRPC) recently participated in a Hari Raya Open House event. The gathering was organised by Malaysia’s Rubber Development Division, which falls under the Ministry of Plantation and Commodities. This occasion allowed the ANRPC to connect with important figures within the natural rubber sector. By bringing together various industry partners, the open house successfully created an atmosphere of goodwill and strengthened existing relationships.

The ANRPC has conveyed its genuine gratitude to the event’s hosts for their warm reception and thoughtful organisation. The association acknowledged the importance of uniting stakeholders in such a meaningful celebration, which helps reinforce shared goals and collaborative spirit across the sector.

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ARLANXEO has officially opened its Innovation Center Asia (ICA) in Changzhou, China, transforming the former Regional Technical Center into a full-fledged Asian innovation hub. This upgrade significantly strengthens the company’s global research and development network, with a clear focus on serving the local Chinese market as well as broader regional needs. The expansion reflects ARLANXEO’s commitment to advancing performance elastomers through targeted regional investment.

Now boasting larger facilities, an expanded team and new laboratory equipment, the Innovation Center Asia is equipped to handle rubber compounding, processing, physical testing, chemical analysis, battery prototyping and more. A dedicated chemistry lab has been added to support the nearby HNBR plant and global HNBR research activities. Located alongside ARLANXEO’s EPDM and HNBR plants in Changzhou, the centre fosters close customer collaboration to address evolving market needs. It also works in tandem with the company’s Dormagen, Germany, innovation centre, jointly developing new testing methods, exploring advanced technologies and delivering innovative product solutions worldwide.

The inauguration event featured speeches from Herman Dikland, ARLANXEO’s Chief Technology and Sustainability Officer, and Hong Sun, Managing Director of ARLANXEO China. Joining them at the ceremony were company representatives, key customers, local government officials and academic partners from various universities. Their presence underscored the collaborative spirit and shared interest in driving innovation forward.

Herman Dikland, Chief Technology and Sustainability Officer, ARLANXEO, said, “Innovation is a core driver of ARLANXEO’s sustainable growth, and China plays an important role in our global innovation ecosystem. This state-of-the-art laboratory facility puts us in an excellent position to advance our R&D capabilities and reinforce our market position. We look forward to driving frontier innovation together with our passionate and creative China team while bringing China-based innovation into solutions for global markets.”

Hong Sun, Managing Director, ARLANXEO China, said, “The inauguration of the Innovation Center Asia reflects our commitment to supporting the rapid transformation of China’s rubber industry during the 15th Five-Year Plan period. With growing demand for advanced materials and customised formulations, the new centre will further strengthen our proximity to customers, enhance our agility in meeting market needs and better support the upgrading of the entire rubber industry.”

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ARLANXEO has strengthened its role in the synthetic rubber industry by expanding its marketing and sales agreement for EPDM rubber produced by Rabigh Refining & Petrochemical Company (PRC), a joint stock company formed under the laws of the Kingdom of Saudi Arabia. This new arrangement became effective in February 2026, granting ARLANXEO exclusive rights to market all EPDM grades coming from PRC’s facilities, which will continue to be sold under the Keltan KSA product name.

This extension of the Keltan KSA business highlights ARLANXEO’s dedicated commitment to the worldwide EPDM market. By combining the original Keltan line with the Keltan KSA portfolio, the company now offers customers a uniquely broad and comprehensive range of EPDM solutions, ensuring a more complete service across diverse applications.

John Sawaya, Chief Business Officer, ARLANXEO, said, “Through this expanded agreement, we are further enhancing ARLANXEO’s position as the global supplier for EPDM synthetic rubber.”

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