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!

Black Swan Graphene Inc. (Black Swan) has formally stated that it has retained DS Market Solutions Inc. (DS Market) to offer market making services in compliance with TSXV standards, subject to the TSXV's approval.

With the aim of improving market depth and raising the liquidity of the company's common shares, DS Market will supply Black Swan with liquidity services in accordance with the terms of TSXV Policy 3.4. In addition to using its own funds to provide the services, DS Market has no direct or indirect stake in Black Swan's securities and no entitlement to purchase them, with the exception of assets required for liquidity. The services are offered by DS Market via Canaccord Direct DMA. DS Market has no direct or indirect stake in the firm or its securities, and Black Swan and DS Market are independent, unaffiliated, and unconnected businesses, reads the statement.

The statement further states that Black Swan will pay DS Market USD 5,000 per month from its available funds in exchange for the services for a minimum of one month, with the agreement being renewed for successive one-month durations. Thirty days before the end of the then-current term, either party may discontinue the agreement by giving writing notice to that effect. On 1 May 2025, DS Market will start offering its services.

The Rubber Board, which is observing its 77th anniversary this year, organised a press conference to showcase a novel method developed by the Rubber Research Institute of India (RRII) for recovering high-quality rubber from skim latex.

The new technique creates rubber lumps by treating the skim latex with a specific chemical mixture for 24 hours, then allowing the acid to coagulate. After that, these lumps may be dried and turned straight into skim crepe. About 3–4 percent of the rubber used to make Centrifuged Latex (Cenex) is skim latex, a by-product of the process. Cenex is frequently used in the production of goods including balloons, condoms, and gloves. About 10 percent of the natural rubber produced in India is converted into Cenex via centrifugation, which is accomplished at more than 40 centrifuging facilities.

The current method for recovering skim rubber is the acid coagulation of skim latex, which produces a slurry of skim rubber. After being packed into many plastic sacks, this slurry is allowed to solidify and dewater for two weeks. Skim crepe is made by further processing the resultant skim powder. But this traditional approach is labour-intensive, unrefined and results in bad odours, and it only generates rubber of poor grade. It has also caused public outcry and legal conflicts in the vicinity of Cenex enterprises, and it presents difficulties for wastewater treatment facilities. With the innovative method created by RRII, plastic bags are no longer used and processing takes only twenty-four hours. In addition to improving environmental sustainability and guaranteeing full recovery of premium rubber from skim latex, it drastically reduces offensive odours.

The Federation of Latex Processors (FLP), a group of owners of centrifuged latex factories, has been granted access to this technology on a fee basis. Other organizations and Cenex units can also purchase it. The product is marketed as Indian Purified Skim Rubber (IPSR) by the Rubber Board, which is also working on a patent for the concept. Rubber companies nationwide have expressed a strong interest in employing IPSR in product manufacture as it provides a competitive edge because of its improved quality and reduced cost.

Several efforts to solve various problems that exist in the rubber value chain were also addressed at the press conference. At the press conference, it was revealed that a nationwide celebration of the Silver Jubilee of the National Institute for Rubber Training (previously the Rubber Training Institute) would be organised, with participation from all relevant parties. M Vasanthagesan IRS (Executive Director, Rubber Board), Dr T Siju (Rubber Production Commissioner), Dr M D Jessy (Director-in-Charge, Rubber Research Institute of India) and representatives of the Federation of Latex Processors were in attendance.

Kraton Corporation, a leading global sustainable producer of speciality polymers and high-value bio-based products derived from pine wood pulping co-products, has expanded its CirKular+ product line with the launch of CirKular+ Paving Circularity Series C5000 in line with its long-term vision to create innovative solutions for a sustainable tomorrow.

The CirKular+ Paving Circularity Series addresses the changing demands of the paving industry to use more reclaimed asphalt and lower greenhouse gas (GHG) emissions. It allows for the addition of up to 50 percent or more reclaimed asphalt to the asphalt mix in surface layers while enhancing performance and processability. It increases the modified asphalt's resilience while maintaining resistance to permanent deformation and lowering the pavement's lifetime carbon footprint.  C5000 satisfies requirements for asphalt surface materials and is compatible with Warm Mix Asphalt technology.

Pedro Lopes, Kraton Global VP of Strategic Marketing, Product Management and Supply Chain, said, “Launching the Paving Circularity Series is a testament to our commitment to sustainability and innovation. In Europe, the paving industry is actively working to increase circularity and reduce GHG emissions in alignment with the European Green Deal and the EU’s 2050 climate neutrality goals. The new series helps unlock value-added circularity by enabling polymer-modified bitumen (PMB) producers and contractors to increase the reuse of reclaimed asphalt, thereby reintegrating it back into the road surface layer.”

Perth-based CTS Tyre Recycling is forging ahead with its plans to reshape the options for disposal of end-of-life tyres in Western Australia.

The company, a part of the wider Cometti Group, a family-owned business with more than 40 years of experience in the tyre industry, has invested more than USD 40 million in a state-of-the-art recycling plant at Neerabup, north of Perth, that processes waste tyres into crumb rubber, tyre derived products, reusable high tensile steel wire and reusable textile. The company also made some additions to its management ranks and expanded its links with industry associations as it moves forward with its strategy. These tyres, along with all other sizes, will be remanufactured in the new Neerabup factory into new, high-value goods like load-restraining matting, gym matting, equestrian and farm matting and acoustic underlay.

Leigh Cometti, the company’s Managing Director, identified a potential to diversify into the recycling of end-of-life tyres, concentrating on some of the huge off-the-road tyres utilised in the mining services and agricultural industries. Over 90 percent of the bigger OTR tyres now in use in Western Australia are thought to end up in landfills. Tyres are commonly buried in pits left behind during excavation, which results in the greatest landfill disposals in the Pilbara area. The recycling programmes will lessen the need for more virgin products in addition to decreasing landfill discharge.

Cometti has brought on two seasoned senior level managers to support him as the company grows. Joseph Jeevaraj has joined as Chief Financial Officer, while Darren Rodwell has been named Chief Operating Officer. Both positions work for the Cometti Group, which also owns the Bunbury Trucks Sales and Service dealership, CTS People and Mechanics Recruitment.