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!

Ecolomondo Corporation, a leading Canadian innovator in sustainable scrap tyre recycling technology, has announced that its new milling line at Hawkesbury facility has achieved a major milestone during recent testing by reaching a throughput of approximately 2,700 lbs per hour of recovered carbon black (rCB). This result surpasses the company’s projected target of 2,200 lbs per hour.

When the new milling line is completely operational, it should be able to process 2,200 pounds of rCB per hour and provide a particle size distribution of 96 percent between 10 and 15 microns. It is anticipated that the plant would process more than 1.5 million scrap tyres annually, recovering 1,350 MT of process gas while producing 4,500 MT of recovered carbon black, 5,400 MT of oil and 2,250 MT of steel.

The company expects the commercial production of rCB to start by the end of May 2025. After being contacted, offtake clients told the company that they were eagerly expecting a larger supply of steel, oil and rCB, said the company. Depending on end-product market pricing, the company's yearly income from the sale of these sustainable goods plus tipping fees of USD 145 per metric tonne is expected to reach USD 12.1 million, with an estimated EBITDA of 45 to 50 percent, added the company statement.

Jean-François Labbé, Interim CEO, Ecolomondo Corporation, said, “This is a major achievement that brings the Hawkesbury facility closer to full production and commercialisation.”

Global speciality chemicals company Orion S.A. has launched a new bio-circular carbon black called ECOLAR 50 POWDER to provide coatings manufacturers with a new solution for more sustainable coatings.

ECOLAR 50 POWDER, which is entirely based on bio-circular feedstock, has coloristic qualities that are on par with those of ordinary speciality carbon blacks and includes 100 percent biogenic raw material according to 14C analysis. The coloristic qualities of ECOLAR 50 POWDER, a low to medium colour furnace black, offer moderate tinting strength and medium jetness in mass tone applications. ECOLAR 50 POWDER offers equivalent coloristic performance for full-tone and tinting applications, as well as comparable wetting and dispersion characteristics to conventionally manufactured low-colour furnace blacks.

ECOLAR 50 POWDER outperformed other common specialist carbon blacks in achieving medium jetness in a solvent-borne alkyd/melamine stoving enamel system. It created a similar neutral undertone as well. When tested in a water-borne 1K PU coating system, ECOLAR 50 POWDER created a more neutral undertone and jetness that was on par with other regular speciality carbon blacks.

Tilo Lindner, Vice President Global Marketing – Speciality Carbon Black, Orion, said, “We’re leading the way in advancing carbon black to meet increasing industry demands for sustainable products. ECOLAR 50 POWDER enables coatings formulators to develop truly sustainable products in all kinds of coatings applications.”

LD Carbon has inaugurated Korea’s first and largest waste tyre pyrolysis plant in Dangjin, South Korea.

Located in the Dangjin Hapdeok General Industrial Complex, the plant is expected to begin full-scale operation next month. The plant is spread over 29,800 square metres and features two factory buildings and five silos. The plant has an annual capacity to process 50 kilotonnes per annum (ktpa) of tyre chips derived from end-of-life tyres (ELTs).

At the location, LD Carbon uses a two-step pyrolysis process, first turning ELTs into solid char and pyrolysis oil. After that, the business uses a secondary pyrolysis process to further compress the char and create recovered carbon black (rCB). It is anticipated that the Dangjin facility would generate 20 ktpa of rCB and 24 ktpa of pyrolysis oil, which is a substantial increase above the combined output of 7 ktpa at its current pilot plant in Gimcheon. When compared to traditional carbon black, the rCB generated by the technique is said to lower carbon emissions by up to 32 ktpa.

The company is planning to build plants overseas and intends to join the Asian market soon. It has also struck a 10-year offtake deal with SK Incheon Petrochem for its pyrolysis oil.

Speciality chemicals company LANXESS India organised its first exclusive Solutions Day event in Mumbai today to showcase its diversified and sustainable product portfolio to customers and other key stakeholders.

The event was organised to promote the idea of ‘One LANXESS’, where its business units – namely Advanced Industrial Intermediates, Flavors & Fragrances, Inorganic Pigments, Liquid Purification Technologies, Lubricant Additives Business, Material Protection Products, Polymer Additives, Rhein Chemie and Saltigo – displayed their distinctive products and solutions at the event. It provided an opportunity to highlight the cross-business synergies that characterise LANXESS' integrated approach and to present the company's cutting-edge solutions designed for a variety of industrial applications.

Three main business sectors, namely Advanced Industrial Intermediates, Speciality Additives and Consumer Protection Products, are currently the emphasis of LANXESS's strategy shift from a polymers to speciality chemicals company. In order to improve the value provided to clients, the event sought to promote cooperation and creativity across these various business divisions. In order to promote knowledge exchange, discover possible areas for collaboration and capitalise on the capabilities of each business unit to propel overall development and success, the day included interactive workshops, technical presentations and networking opportunities.

Namitesh Roy Choudhury, Vice Chairman & Managing Director, LANXESS India, said “Our goal with Solutions Day is to strengthen our existing partnerships and explore future collaborations that support sustainable industry growth. Through this event, we want to highlight LANXESS’ integrated offerings to all our stakeholders and address the global industrial challenges through the combined power of sustainable chemistry, innovation and responsible business.”