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.

Nouryon, a leading supplier of organic peroxides and a developer of organic peroxide solutions, has formally announced the completion of capacity expansion of its organic peroxides manufacturing facility in Ningbo, China.

The company's production capacity for Perkadox 14 and Trigonox 101 organic peroxide products, which are crucial components for altering polymer characteristics and crosslinking rubbers and thermoplastics, has increased to 6,000 tonnes each as a result of this capacity expansion. Furthermore, by improving the qualities of recycled polypropylene (R-PP), these solutions can also allow consumers to employ recycled polymers in applications that were previously exclusive to virgin plastics.

Alain Rynwalt, Senior Vice President – Performance Materials, Nouryon, said, “Nouryon is a world leader in essential ingredients for the polymer industry and this expansion highlights our dedication to supporting our customers’ growth across the entire polymer cycle. Customer interest in improving the properties of recycled polypropylene continues to rise, in line with increased consumer awareness and more stringent regulations.”

Sobers Sethi, Senior Vice President – Emerging Markets and China, Nouryon, said, “Asia Pacific is a key region for Nouryon and our most recent expansion in China strengthens our supply position even more in this growing region. Our customers rely on our existing network of manufacturing facilities and innovative technologies, and we are pleased to build more capacity to meet growing customer demand around the world.”

Trinseo, a speciality materials solutions provider, has signed agreements to supply its polycarbonate technology license as well as all proprietary polycarbonate production equipment in Stade, Germany to Deepak Chem Tech Ltd, a wholly owned subsidiary of Deepak Nitrite Limited, a diversified chemical intermediates company based in Vadodara, Gujarat, India.

The combined deals are worth USD 52.5 million. Subject to significant milestones, the business anticipates receiving around USD 9 million by the end of 2024 and an additional USD 21 million in the first part of 2025. The firm has made the decision to leave Stade, Germany, with this disposal of the production assets.

Frank Bozich, President and Chief Executive Officer, Trinseo, said, “While Trinseo recently announced its decision to exit virgin polycarbonate production, our polycarbonate technology is highly valued and the manufacturing equipment in Stade, Germany, can be utilised in India by Deepak. These are the initial steps of a strategic, collaborative partnership with Deepak, as we explore additional opportunities to leverage our technology portfolio and expand in higher-growth areas such as India.”

China's butadiene exports have experienced significant growth in recent years, particularly in 2021 and 2024. According to Sublime China Information (SCI), this surge is primarily driven by supply constraints in key regions, including the US and Southeast Asia.

Export Volume and Price Trends

In 2021, China's butadiene exports reached a historic high due to a supply gap in the US market. According to SCI, this trend continued in 2024 as reduced deep-sea cargo shipments and production challenges in Southeast Asia further tightened global supplies. From January to September 2024, China's total butadiene exports surged by 111 percent year-over-year to approximately 120.8 kilo tonnes.

The average export price of butadiene has fluctuated over the past five years. In 2023, weak demand in South Korea and competition from deep-sea cargoes led to a significant decline in export prices. However, in 2024, supply shortages from key regions drove prices to a five-year high. As of September 2024, the average export price reached USD 1,391 per metric ton, a 35 percent month-over-month increase, added SCI.

Export Destinations and Regional Dynamics

The majority of China's butadiene exports are directed to South Korea and Taiwan. In 2024, South Korea accounted for 74 percent of total exports, a significant increase from the previous year. This surge was driven by factors such as limited domestic supply and increased demand for spot butadiene.

While China's butadiene exports have been strong, the long-term potential for significant growth in deep-sea exports remains limited due to established supply chains and regional demand dynamics. Most of China's exports are currently concentrated in Northeast Asia, with limited opportunities for expansion into other regions.

Future Outlook

SCI added that 2025 China's butadiene supply is expected to be relatively sufficient, and export volumes may increase further. However, the sustained growth of exports will depend on various factors, including downstream demand in key markets, the availability of deep-sea cargoes, and the development of new production capacities in other regions.

Despite these uncertainties, China's butadiene industry is well-positioned to capitalize on global supply-demand imbalances and continue to play a significant role in the global market.

Cabot Corporation, a global speciality chemicals and performance materials company, has announced through an official statement that it will raise prices globally for carbon black products sold by its speciality carbons business. The price rise will be global and will come into effect for all shipments on or after 1 December 2024, or as contracts allow.

The company claims that the price rise is necessary owing to the impact of inflation on labour, maintenance and other production activities, as well as supply chain-related expenditures. The price increase will vary depending on the product and region.

The statement further elaborates that these price adjustments will help the company remain a dependable, long-term provider of high-quality products and services to its consumers. Cabot also underlined its commitment to guaranteeing supply security and the best service standards for its clients, as well as providing technological and process improvements and moving forward with its environmental goals.