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.

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.”