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.

Comments (0)

ADD COMMENT

Link Copied!

In pursuit of its strategic vision, ‘Michelin in Motion 2030’, Michelin is expanding into high-value adjacent markets, including the development of its Polymer Composite Solutions. A key step in this growth is the acquisition of Flexitallic, a global leader in sealing solutions based in Houston, Texas. This move is set to substantially enhance Michelin’s sealing portfolio and extend its market access, particularly within the aftermarket sector.

Flexitallic serves critical industries such as energy and chemicals, providing high-performance gaskets, sheet products and specialty filler materials known for exceptional reliability and resistance in extreme, safety-critical environments. The company, which operates 17 facilities worldwide and employs about 1,200 people, reported sales of approximately USD 220 million in 2025.

The acquisition is a strong strategic fit, uniting two global organisations with a shared commitment to innovation and quality, thereby creating significant synergies for future growth. The transaction, for an undisclosed amount, will be fully financed from Michelin’s available cash. Subject to standard regulatory approvals and closing adjustments, it is anticipated to be finalised in the first half of 2026.

Comments (0)

ADD COMMENT

Link Copied!

Birla Carbon has inaugurated a dedicated production line at its Trecate, Italy facility, specifically engineered for the finishing and packaging of its Continua Sustainable Carbonaceous Material (SCM). This industry-leading circular material is produced from end-of-life tyres, and the new line enables its manufacture in large, consistent volumes. This expansion directly strengthens long-term supply security for the company’s worldwide customer base.

The Continua SCM range, including the 8000 series for tyres, rubber goods and plastics, provides a scalable sustainable solution. It allows customers to increase recycled content while gaining functional benefits such as blending flexibility and lower homologation costs. Importantly, it delivers assured regulatory compliance and consistent quality, supporting industries in their transition toward enhanced product circularity and reduced environmental impact.

John Loudermilk, President and CEO, Birla Carbon, said, “This is a pivotal moment for Birla Carbon. Continua SCM represents the most consistent, high-quality, circular material in the carbon black industry today and replaces a portion of carbon black in most rubber and non-rubber applications. It also reflects cross-industry collaboration for sustainability, with raw material sourced from our partner Circtec’s newly launched tire pyrolysis facility in the Netherlands and finished and packed at our state of-the-art processing line in Trecate. The launch of this line is a key milestone in our ambition to put back into industry 300,000 tonnes of end-of-life tyres annually by 2030, contributing to our aspiration to achieve net zero carbon emissions by 2050.”

John Davidson, Chief Sales, Marketing and Sustainability Officer, Birla Carbon, said, “The launch of the Continua SCM processing line in Trecate ramps up the availability of our circular product portfolio for customers globally. Continua SCM enables our customers to increase the use of sustainable materials in their products while maintaining the performance standards they expect. This expansion reinforces our commitment to supporting customer sustainability goals at scale.”

Comments (0)

ADD COMMENT

Link Copied!

German chemical group WACKER has announced significant price increases for a wide range of silicone products, effective from 1 February 2026. These adjustments, which will see prices rise by up to 25 percent or even higher in specific instances, will be applied across existing customer contracts as necessary. The decision is a direct response to unprecedented surges in raw material costs, most notably for the precious metal platinum, a critical catalyst used in the production of addition-curing silicone products and crosslinking silicone release agents.

According to Tom Koini, Head of Silicones, the extreme market dynamics have made this step unavoidable, as internal efficiency measures can no longer absorb the cost pressure. Platinum prices on international commodity exchanges have more than doubled since the beginning of the previous year. WACKER states that the price adjustments are essential to maintain its high standards of product quality, customer service and technical support moving forward. The increases will specifically affect addition-curing silicone rubber grades, silicone resins, silanes and silicone-based release coatings.

The company’s Silicones division, a global leader with a portfolio of over 2,800 specialised products, serves key industries including automotive, pharmaceuticals, medical technology, electrical engineering and energy transmission. The portfolio encompasses silicone fluids, elastomers, resins, sealants, silanes and release coatings, all designed to enhance the performance and value of end products. In 2024, this division accounted for approximately 49 percent of the Group’s total sales.

Comments (0)

ADD COMMENT

Link Copied!

ARLANXEO, a leading performance elastomers company, has officially opened its new Therban hydrogenated nitrile butadiene rubber (HNBR) production facility in Changzhou, China. This advanced plant, dedicated to producing the Therban brand, is designed to meet rising demand across vital industries including new energy, automotive, aerospace and next-generation battery technologies, where materials must endure extreme operational conditions.

Strategically positioned within ARLANXEO’s existing Changzhou complex, which also houses an EPDM plant and a Regional Technology Centre, the new installation strengthens the company’s integrated approach from innovation to manufacturing. It forms a crucial part of a global production network that includes sites in United States and Germany, establishing Changzhou as a central hub for the Asia-Pacific region.

The facility boasts an annual design capacity of 5,000 tonnes, with the first phase of 2,500 tonnes having successfully commenced operations in October 2025. It was completed with an exemplary safety record, achieving over 1.1 million incident-free work hours throughout its construction and commissioning, which was concluded within 13 months.

Engineered for high efficiency and environmental responsibility, the plant incorporates state-of-the-art finishing technology for consistent product quality. A key feature is an advanced thermal oxidation system that recovers energy and cuts carbon emissions in core processes by approximately 80 percent compared to traditional methods. Furthermore, the facility employs a closed-loop design that eliminates routine process wastewater discharge, supporting ARLANXEO’s commitment to reducing greenhouse gas emissions.

The inauguration was marked by a ceremony attended by senior leadership from ARLANXEO and its shareholder committee, alongside representatives from key customers, local authorities and community partners. This expansion significantly enhances ARLANXEO’s ability to supply reliable, high-performance elastomer solutions to its regional customer base.

Dr Faisal Al Faqeer, ARLANXEO Shareholders’ Committee Chairman and Aramco Senior Vice President of In-Kingdom Liquids to Chemicals Development, said, “China is important in supporting Aramco’s downstream growth. ARLANXEO’s new Therban® HNBR plant is the most recent demonstration of Aramco’s downstream expansion strategy of portfolio diversification and integration, underscoring our confidence in China’s innovation and manufacturing strength. We look forward to deepening our cooperation and further contributing to China’s high-quality and sustainable growth.”

Stephan van Santbrink, CEO, ARLANXEO, said, “Today’s inauguration marks an important milestone for ARLANXEO and a strong demonstration of our long-term commitment to China. We sincerely thank the Changzhou government, Aramco and all stakeholders for their trust and continued support. With the new HNBR plant now fully operational, we are further integrating our local production and R&D capabilities to strengthen the resilience of our global supply network. By delivering locally produced, high-quality rubber products, we will continue to collaborate with our customers and accelerate application innovation, creating greater economic and social value across our value chain.”

Comments (0)

ADD COMMENT

Link Copied!