Elastomer tackifiers are those that produce green tack in elastomers. The term “tack” refers to the ability of two uncured rubber materials to resist separation after bringing them into contact for a short time under relatively high pressure. Building tack of rubber components is an important pre-requisite to enable tyre building on the tyre building drum where different rubber layers are put together on the tyre building drum before they are cured. Another important property of tackifier is, it should retain its tack on storage. A good tackifier, therefore, should have the following properties :

• Very high initial and extreme long-term tackiness
• No adverse effect on the rubber compound cure on scorch
• No interference on (a) rubber to metal bonding (b) rubber to fabric bonding
• Physical properties of the cured rubber remain unchanged
• No effect on the performance of aged rubber compound properties
• Improves rubber compound process reliability
• Show extreme good performance in silica / s-SBR based rubber compound.

In general, NR has enough tack because of the presence of a very high quantity of low molecular weight fraction, having its wide molecular weight distribution. Its low molecular weight fraction also generates during its break down in machines. On the contrary, synthetic rubber lack in tack property because of the absence of enough low molecular weight fraction in them, having narrow molecular weight distribute on (Fig.1). Synthetic rubber also resists in the molecular break down upon mastication and therefore, cannot produce low molecular weight fraction. Resins are typically produced with molecular weights (Mw) between 1,000 and 2,000 with maximum Mw around 3000. The molecular weight is important since tackifying resins work at the surface of the rubber compound and must be able to migrate to the surface to be effective. If the molecular weight is too low, the resin will remain soluble in the elastomer and not migrate its way to the surface. If the molecular weight is too high, the elastomer will be insoluble in the elastomer. Rubber industries use both synthetic and natural resins for tack. Following three types are in major use in the industry :

1. Aromatic Resins (Phenolic, Cumaron Indane)
2. Petroleum based resins
3. Plant Resins ( wood rosin resins,Terpene resins)

Only plant resin is a source of natural resins. However, due to product consistency and different compatibility factors, synthetic resins are in major use. Besides tyre and other rubber applications, the major end-uses for resins are in pressure-sensitive adhesives, hot-melt adhesives, road markings, paints, caulks, and sealants. Manufacturers use hydrocarbon resins to produce hot melt adhesives (for infant and feminine) and packaging applications in addition to glue sticks, tapes, labels and other adhesive applications. All resins are sticky and because of their low molecular weight they migrate (diffuse) easily on the rubber product surface and behaves sticky and that causes tack. Tack property is apparently due to two major reasons :

• Spontaneous diffusion of molecules between two uncured rubber layers.
• Strong molecular forces resulting high degree of crystallinity

Highest level of tack in NR could be due to both the reasons, which means, NR has a high degree of crystallinity (stress induced crystallization) and it has also broad (wider) molecular weight distribution (Fig.1), so that, having plenty of lower molecular fraction can diffuse faster between two layers in contact each other. NR is reported to improve upon its tack on mastication because it generates a higher number of lower molecular weight fraction chains upon breaking down on shearing forces in machines. CR (Neoprene Rubber) shows exceptional adhesive property because it shows the highest degree of crystallinity, even much greater than NR, due to its strong intermolecular attractive force.

Honestly, NR may not require any tackifier because it has enough low molecular weight fraction of chain molecules, due to its wider molecular weight distribution (Fig.1), to be migrated on the rubber component surface and can produce enough tack. It loses its tack mostly because it might have been processed at a higher temperature and is already in the premature vulcanization stage. It can also happen due to the fact that although calendaring or extrusions were done at the right temperature stock was made before adequate cooling and thereby allowed scorching in windup liners. It also loses its tack at cold ambient temperature, in the rainy season and also if the filler level is too high or if the viscosity of the stock is substantially higher than required. However, all synthetic rubber or when synthetic rubber (SBR,BR) is blended with NR, may require to add adequate resins for compound processing.

Except C4,C5 petroleum-based resins, all other types of resins are compatible with NR and is added 1-2 phr. Comparatively C9 petroleum-based resin is better in NR.  Plant-based resins are found to work better in 100% NR. When NR is compounded with synthetic rubber, the tackifier is a must and the dose could be as high as 2-4 phr depending on the content of synthetic rubber, oil and filler in the compound matrix.  All synthetic rubber lag in rubber tack because, in general, synthetic rubber has :

• Narrow molecular weight distribution
• It resisting break down of molecular chains under mechanical shear
• Synthetic rubber is in very pure form

Aromatic Resins (Phenolic, Cumaron Indane) work better in SBR and BR than plant based resins. For hydrocarbon type of elastomers like butyl , halobutyl , EPM and EPDM , petroleum base resin (C4,C5) work better and usually added with 1-2 phr in the formulation, However, with a higher dose of filler, 2-4 phr tackifier could also be added.

Tackifier resins are added to base polymers/elastomers not only  to improve tack (ability to stick) but it also helps in better wetting with filler. Increase in tensile strength by adding resins has been witnessed in different types of elastomers, aromatic resins have been witnessed to increase tensile strength of SBR and its blend.

Effect of Environment on Rubber Tack

The tack of a rubber article is greatly affected by environmental conditions such

as temperature, ozone level and humidity. Environment can not influence tack, however,  if processed rubber compound is used with in 24 hrs. High temperature and humidity conditions have a detrimental effect on the initial tack and tack retention of an elastomer. Phenolic tackifying resins can help improve tack under these conditions, but they have their limits under extreme conditions. Superior tack retention under the influence of high humidity can be often be achieved with epoxy resin modified alkylphenol-formaldehyde polymers.

Hydrocarbon based tackifying resins are sometimes used as a low-cost alternative to phenolic tackifying resins. However, hydrocarbon resins are not as effective at maintaining tack under adverse environmental conditions, like elevated temperature and high humidity, nor do they have the same tack retention. Hydrocarbon resins however, preferred in butyl and EPDM rubber compound due to their compatibility.

Hydrocarbon resins are not as efficient as phenolic tackifying resins, and higher levels are often required to achieve the same tack. High tackifier resin levels can cause a loss in tensile strength, tear strength and, most importantly, hysteresis. In applications where these properties, especially hysteresis, are important, phenolic tackifying resins are excellent choices and should be used.

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The Association of Natural Rubber Producing Countries (ANRPC) has released its Monthly Natural Rubber Statistical Report for June 2026, a month defined by price resilience amid conflicting market forces. The provisional reopening of the Strait of Hormuz triggered a sharp 20.29 percent drop in Brent crude oil prices to USD 85.40 per barrel. However, this bearish signal was counterbalanced by persistent supply constraints from El Niño-related weather disruptions across major producing regions.

Physical rubber prices posted broad-based gains across most grades. SMR-20 rose 1.39 percent to USD 2.32 per kilogramme, while STR-20 gained 2.61 percent to USD 2.55 per kilogramme. RSS-3 and RSS-4 advanced 4.98 percent and 5.88 percent to USD 3.09 and USD 2.84 per kilogramme, respectively, though latex eased 1.44 percent to USD 1.94 per kilogramme. On the trade front, China's imports surged 7.14 percent month-on-month, while India and Viet Nam declined. Export growth was recorded for Cambodia, Viet Nam and Indonesia, though Thai shipments contracted.

Global production for 2026 is projected at 15.310 million tonnes, up 2.3 percent from 2025, driven by gains in Thailand, China, India and Malaysia. However, June output fell 3.7 percent year-on-year to 1.207 million tonnes due to seasonal wintering and El Niño-related weather disruptions. Malaysia, Indonesia and Cambodia have introduced new incentive and governance measures to strengthen their sectors. Global consumption is forecast to grow 0.7 percent to 15.411 million tonnes in 2026, with June consumption rising 3.3 percent to 1.300 million tonnes, led by China and India amid steady tyre and EV-related demand.

Currency markets saw the Malaysian ringgit trade between RM3.96 and RM4.08 against the US dollar, while the Thai baht ranged from 32.56 to 33.24. In futures trading, the SHFE September 2026 contract averaged 17,580.68 CNY per tonne, down 0.45 percent month-on-month, while the SGX September contract averaged USD 2.24 per kilogramme, up 1.75 percent, with both reflecting tightening supply and firm downstream demand.

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Pyrum Innovations AG has finalised long-term supply and offtake agreements with Pirelli, reinforcing the tyre manufacturer’s European Tyre-to-Tyre initiative. The deal secures Pirelli’s purchase of Pyrum’s ThermoTireBlack (TTB) for use in its European production facilities, while Pirelli will provide Pyrum with end-of-life tyres from designated German sources.

These contracts simultaneously bolster Pyrum’s feedstock security and guarantee an industrial outlet for its recycled materials, covering both raw material procurement and product commercialisation. Through its proprietary thermolysis process, Pyrum transforms scrap tyres into ThermoTireBlack, which can substitute fossil-based carbon black, and ThermoTireOil (TTO), destined for chemical industry use. The partnership offers further validation of Pyrum’s technology within a certified European value chain involving tyre, chemical and synthetic-rubber leaders.

Pyrum also supports the broader Tyre-to-Tyre project, initiated by Pirelli with BASF and Synthos, which reintroduces secondary materials from used tyres and production waste into new tyre manufacturing via an ISCC PLUS-certified, traceable system.

Pascal Klein, CEO, Pyrum Innovations AG, said, “Signing these long-term agreements with Pirelli is an important commercial and strategic milestone for Pyrum. The coöperation secures both the supply of end-of-life tyres and an industrial outlet for our TTB. It confirms that our technology and products meet the requirements of one of the world’s leading tyre manufacturers and can contribute to the establishment of scalable circular value chains in Europe.”

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MICHELIN ResiCare, a specialist in renewable and high-performance chemical solutions, has entered into a distribution partnership with IMCD Europe, a major international distributor of speciality chemicals. The agreement centres on the European supply of 5-hydroxymethylfurfural (5-HMF), a bio-sourced compound produced at the company's Isère-based industrial facility in Péage-de-Roussillon.

Under the new arrangement, IMCD Europe will handle distribution across the continent while MICHELIN ResiCare maintains direct engagement with its key strategic accounts. The collaboration aims to significantly widen the molecule's availability to European manufacturers through an optimised logistics framework and localised technical support, thereby addressing rapidly growing demand within the materials and formulation chemical sectors.

The French production site, scheduled to begin operations in early 2027, will have an initial annual capacity of 3,000 metric tonnes. This domestic manufacturing capability represents a critical step in securing European access to a molecule deemed strategically important for the region's chemical industry, reducing reliance on external supply sources.

IMCD will contribute its technical expertise, market knowledge and pan-European distribution network to facilitate the integration of 5-HMF into new applications. The company's established footprint in polymers, advanced materials and speciality formulations positions it to provide developmental support to manufacturers exploring alternatives to fossil-derived intermediates. MICHELIN ResiCare has already spent two years assisting major industry players with application evaluations, and the partnership is expected to expand these efforts across a broader customer base.

Derived from fructose through non-toxic green chemistry and already REACH-registered, 5-HMF serves as a versatile building block for low-environmental-impact resins and can replace conventional petroleum-based ingredients across diverse industries including agriculture, cosmetics, construction, transport, aeronautics and electronics. The collaboration reinforces MICHELIN ResiCare's commitment to renewable resources and sustainable material development while aligning with IMCD's dedication to advancing innovation in greener chemistry solutions.

Laurent Lemonnier, CEO, MICHELIN ResiCare, said, “This partnership with IMCD represents a major step forward in our desire to popularise the use of 5-HMF and to support the transition to a more responsible chemistry. With its technical expertise, its capacity to support customers and its European location, IMCD is the perfect partner to speed up the distribution of this molecule of the future.”

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Pirelli, Pyrum, Synthos and BASF have launched a European tyre-to-tyre recycling initiative aimed at increasing the use of recycled materials from end-of-life and scrap tyres in the manufacture of new tyres. The project, coordinated by Pirelli, is designed to establish an industrial ecosystem that supports a circular economy while reducing reliance on virgin raw materials.

The initiative uses end-of-life tyres collected across Germany from selected Driver retail outlets and motorsport activities, together with scrap tyres from Pirelli's Breuberg manufacturing plant. These materials are processed into secondary raw materials, including synthetic rubber, certified under the ISCC PLUS scheme to ensure traceability throughout the value chain before being reintroduced into the production of new Pirelli tyres.

Under the process, Pyrum converts end-of-life and scrap tyres through pyrolysis into recovered carbon black (rCB) and tyre pyrolysis oil (TPO). The recovered carbon black is upgraded and used in Pirelli's European tyre production, replacing part of the virgin carbon black requirement.

The tyre pyrolysis oil is supplied to BASF, where it is co-fed with fossil-based feedstock in the production of chemicals including butadiene and styrene. Using a mass balance approach, the recycled content is allocated to ISCC PLUS-certified Ccycled® products. Synthos then uses these materials to manufacture ISCC PLUS-certified synthetic rubber for high-performance tyre applications, which is supplied back to Pirelli, completing the material loop.

The companies said the project demonstrates that large-scale product circularity requires collaboration across the value chain rather than action by a single company. The partnership combines material science, certified processes and industrial capabilities to recover, process and reuse materials within a structured system.

According to the companies, the project represents the most comprehensive application of a tyre-to-tyre circular model in Europe to date, showing how end-of-life tyres can be transformed into raw materials for new tyre production through a traceable industrial process.

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