• Plastic ( soft or malleable) at normal ambient temperatures
• A melting point above approximately 45 °C.
• A  relatively low viscosity when melted (unlike many plastics)
• Insoluble in water
• Hydrophobic

We shall be discussing here on the waxes which are only being used in the rubber and plastic industry. Beeswax, perhaps , is the first wax which used by human in the beginning of our civilization, was one of the important renewable source of fuel. The honey comb formed by bees has typical hexagonal geometric pattern (Fig.1). Bees wax is used in tire building drum, if the rubber is too sticky, it can also be used in two roll mill to take care of rubber sticking to the rolls. It is frequently being used in the BC, MC, PC, TB  inner-tube making industry during pre-forming operation in the green stage when inner-tubes are expanded under mild air pressure just before curing in mold.

The main commercial source of wax is, however, crude oil but not all crude oil refiners produce wax. "Mineral" wax can also be produced from lignite. Plants, animals and even insects produce materials sold in commerce as "wax". There are five categories of waxes being used in rubber industries :

• Bees Wax
• Paraffin Wax - made of long-chain alkane hydrocarbons
• Microcrystalline Wax - with very fine crystalline structure
• Chlorinated Paraffin Wax
• Polyethylene Wax
• Chlorinated Polyethylene Wax

The major uses of petroleum based waxes are in rubber, cosmetics and in Candle industry. They are generally white in color but show usual brown color (Fig.2) due to contaminated with oil traces. Two types of waxes, in general, are used in rubber industry, Paraffinic wax and Microcrystalline wax. Its normal dose is 1-3 phr and high level of wax impairs low temperature flexibility and compression set. Rubber compounder considers wax as a very important processing aid because it has following advantages:

• Improves mixing properties

  

   

• Improves dispersion of filler and other ingredients
• Improves extrusion properties
• Improves upon extrudate and calendared surface finish
• Protects surface and acts as antioxidant /antiozonate

Paraffin and Microcrystalline waxes are derived from petroleum. They are easy to recover and offer a wide range of physical properties that can often be tailored by refining processes. Most producers offer two distinct types of petroleum waxes: paraffins, which are distinguished by large, well formed crystals; and microcrystallines, which are higher melting waxes with small, irregular crystals. Microcrystalline wax contains substantial proportions of branched and cyclic saturated hydrocarbons in addition to normal alkanes.

Some producers also sell "intermediate" wax, in which the boiling range is cut where the transition in crystal size and structure occur. Petroleum wax producers also characterize wax by degree of refinement; fully refined paraffin has oil content generally less than 0.5% and fully-refined micro-crystalline less than 3%. Paraffin wax produced from petroleum is essentially a pure mixture of normal and iso-alkanes without the esters, acids, etc. found in the animal and vegetable-based waxes.

Paraffin wax (or simply "paraffin") is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 47-64 °C  and having a density of around 0.9 g/cm³. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents, but burns readily. Paraffin wax is generally unbranched hydrocarbon having carbon above C₁₇ and  are solid at room temperature. Their carbon atoms typically ranges between C₁₇ - C₃₀ and having typical melting point around 60°C. All paraffinic wax are recovered from fractional distillation of petroleum.The name paraffin implies that it contains straight hydrocarbon structure but it has branch also. Branched paraffins are called ‘Isoparafins’ and cyclic parafins are called ‘Cresines’ or ‘Isoceresies’.

Pure paraffin wax dose in rubber compounding varies from 1-3 phr. Pure paraffin wax is rarely used these days in rubber industry as it has oozing character and in excess it causes blooming on green rubber components, that results in reduction in compound tack. They are frequently blended with microcrystalline wax in rubber compounding therefore.

Pure paraffin wax is an excellent electrical insulator, with an electrical resistivity of between 10¹³ and 10¹⁷ ohm meter. This is better than nearly all other materials except some plastics (notably teflon or polytetrafluoroethylene). It is an effective neutron moderator and was used in James Chadwick's 1932 experiments to identify the neutron. Paraffin wax (C₂₅H₅₂) is an excellent material to store heat, having a specific heat capacity of 2.14–2.9 J g^–1 K^–1 (joule per gram per kelvin) and a heat of fusion of 200–220 J g^–1(joule per gram). This property is exploited in modified drywall for home building material.

Microcrystalline waxes: This is produced by de-oiling petrolatum, as part of the petroleum refining process. Microcrystalline wax contains a higher percentage of isoparaffinic (branched) hydrocarbons and naphthenic hydrocarbons. It is characterized by the fineness of its crystals in contrast to the larger crystal of paraffin wax. It consists of high molecular weight saturated aliphatic hydrocarbons with comparatively higher melting point than paraffinic wax. It is generally darker, more viscous, denser, tackier and more elastic than paraffin waxes. The elastic and adhesive characteristics of microcrystalline waxes are related to the non-straight chain components which they contain. Typical microcrystalline wax crystal structure is small and thin, making them more flexible than paraffin wax. It is commonly used in rubber formulation and cosmetic formulations.

Its usual carbon atom ranges from C₄₀–C₇₀ , having comparatively higher melting point (Fig.4) between 80-105 ⁰C because they have higher number of carbon. Common dose in rubber compounding is between 1-3 phr. Some time higher dose of  100% Micro crystalline wax is difficult to process and as a result they are often blended with paraffinic wax for rubber use. Blending is also done for economical reasons as microcrystalline wax is comparatively costlier. Paraffinic wax, having smaller molecular weight bleeds faster in cured rubber article, whereas, 100% micro crystalline wax  will have inherent resistance to faster volatilization and eventually, blended wax will have an intermediate property. Refineries may also utilize blending facilities to combine paraffin and microcrystalline waxes. This type of activity is prevalent especially for industries such as tire and rubber industries.

Higher dose of antioxidant and anti ozonates are always advised to add along with microcrystalline wax because the later help slower migration of antioxidant and antiozonates on the product surface and thereby increase on the product durability against ageing process. Tire curing bladder is often blended with 1-3 phr of microcrystalline wax.

Chlorinated Paraffin Wax

Upon chlorination of paraffinic wax we get Chlorinated Paraffin Wax(CPW). This is available in batch process that is processed from effective exothermic reaction. This reaction generates a by-product hydrochloric acid that is later removed out of the solution. Finally stabilizer and solution is mixed that provide the required final product, which is used in various industrial applications. With 30 to 70% chlorine and insolubility in water, these CPWs have low vapor pressure. Chlorinated Paraffin Wax is highly inert, insoluble in water and they have low vapor pressure. Generally used as plasticizers in plastic and elastomers, where flame retardant property is important.

Polyethylene waxes (PE-Wax)

Polyethylene waxes or PE-Wax is same familiar polyethylene chemical structure (Fig.5) but with lower molecular weight , generally around or less than 3000.This is a processing aid in elastomer and plastics but basically they are a form of synthetic resins. It is a white solid product (Fig.6) appears in the market as powdery, lumpy, or flaky product. It is a non-toxic product having concentrated distribution of molecular weight of 1500 with specific gravity about 0.94 with high softening point but low fusion viscosity with melting point; 112 - 118°C, melt peak 110 °C, flash point 210°C, minimum. It has excellent stability against polishing, scratch resistance, metal mark resistance, scuff resistance. PE-Wax is resistant to water and chemical materials.

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Solvay is expanding its global circular economy strategy by converting its Asian production of highly dispersible silica (HDS) to use certified circular raw materials. Beginning in 2026, its plants in Qingdao, China, and Gunsan, South Korea, will transition to using ISCC+ certified waste sand. This major initiative is projected to make over half of the region’s HDS output circular, directly aiding tyre makers in their goal of incorporating over 40 percent sustainable materials by 2030.

This transition provides tyre manufacturers with a cost-effective, high-volume circular Zeosil silica that integrates seamlessly into existing processes without the need for reformulation. The move builds on the successful conversion of Solvay’s Livorno, Italy, facility to using rice husk ash and reflects a coordinated, global shift towards circular sourcing. It also supports the broader sustainability goals of Solvay Silica, including the adoption of low-emission technologies like electric furnaces to minimise the carbon footprint of its products worldwide.

By pioneering circular silica from diverse feedstocks and regions, Solvay is fostering more resilient and sustainable supply chains through innovative partnerships across the entire value chain.

An Nuyttens, President of Solvay’s Silica Business unit, said, “Solvay’s circular silica helps improve fuel efficiency and EV range, offers long-lasting wear benefits, improves safety, while advancing sustainability. This is more than innovation - it’s a reinvention of how we source, produce and collaborate across the value chain.”

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Following the formal approval of its foundational design, Sinopec has announced the construction of a new green, high-end rubber materials facility in Tianjin, China. The project, which was initially revealed in 2023, represents a total investment of CNY 2.452 billion (approximately USD 344.65 million). Its production output will include 100 kilotonne per annum (ktpa) of solution styrene butadiene rubber and an equal volume of nickel-based butadiene rubber.

Operated by Sinopec’s Beijing Yanshan branch, the venture will be funded through a combination of 70 percent bank loans and 30 percent company capital. The initial construction phase, focused on piling work for processing units, storage areas and auxiliary facilities, is valued at CNY 28 million (approximately USD 3.94 million) and scheduled for completion within 31 days.

This new rubber plant is an integral component of the larger Sinopec Nangang high-end materials industrial cluster, which also features a recently completed 1.2 million tonne-per-year ethylene complex. Encompassing a 277,004 sqm site with a built area of 43,522 sqm, the facility is projected to become operational in 2027.

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Elkem ASA, a global leader in advanced silicon-based materials, has announced a significant advancement in silicone sustainability with the successful validation of a new mechanical recycling process for High Consistency Rubbers (HCR). This innovation provides a scalable method for recycling crosslinked HCR waste and reintroducing it into new product formulations. The process achieves re-incorporation rates of over 50 percent while maintaining the excellent mechanical properties required for high-performance applications. This breakthrough demonstrates how material engineering can enable a more circular economy for silicones, helping to reduce waste and the carbon footprint while meeting rising market demand for sustainable solutions.

This mechanical recycling process expands Elkem's comprehensive silicone recycling strategy, which now encompasses both chemical and mechanical pathways. The ability to integrate multiple recycling technologies allows the company to tailor its approach based on the type of waste material, specific carbon reduction goals and the performance needs of the final product.

The development is a key outcome of the open innovation project ‘RENOV’ (Recycling & Reincorporation of Elastomer Materials), focused on creating technologies for recycling and reincorporating crosslinked elastomer waste. The project, supported by the French environment agency ADEME, unites Elkem with industrial partners Hutchinson and Nexans, as well as several CNRS-affiliated laboratories. A primary objective is to evaluate market acceptance and identify the most promising commercial and environmental applications for mechanically recycled HCR.

High Consistency Rubbers are valued for their exceptional strength, thermal stability and electrical insulation properties, making them critical components in industries ranging from electric vehicles and aerospace to medical devices and electronics. Elkem will present samples of the recycled material and detail this new technology at the K 2025 trade fair in Düsseldorf, Germany, from 7–14 October 2025.

Joséphine Munsch, R&T sustainability leader at Elkem, said, “This breakthrough demonstrates the power of purpose-driven innovation aligned with market expectations. After two years of development, we are proud to present a first proof of concept for mechanical recycling of HCR, opening the door to new industrial applications and reinforcing our ambition to leverage pragmatic, science-driven solutions to lead and accelerate the transition to a circular economy for silicones.”

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ContiTech, a group sector of Continental, has officially launched production at its new USD 90-million hydraulic hose manufacturing facility in Aguascalientes, Mexico. This significant investment is a strategic move to reinforce local supply chains, boost regional production capacity and position innovative fluid power solutions closer to its customer base across North America.

The new 900,000-square-foot plant will produce high-performance hoses for numerous industrial and mobile applications, serving vital sectors such as construction, agriculture, mining and energy. It has been designed to operate in a tightly coordinated network with ContiTech’s existing facility in Norfolk, Nebraska. This dual-plant strategy enhances production flexibility, improves operational efficiency and allows the company to be more responsive to evolving customer demands by strategically balancing technology, volume and lead times.

This expansion underscores ContiTech's long-term commitment to growth in key markets through substantial investment in local infrastructure and talent. Production at the Aguascalientes site will be gradually increased, with the first customer deliveries anticipated to commence in the fourth quarter of 2025.

Philip Nelles, Member of the Continental Executive Board and CEO of the ContiTech group sector, said, “The start of production in Aguascalientes marks a key milestone in ContiTech’s journey towards being a more agile, regionalised partner to our customers. At ContiTech, we build on 150 years of materials expertise. While our portfolio is broad and diverse, all our solutions are grounded in the same strength: high-performance materials that are mission critical, innovative and engineered to perform. Whether they connect, convey or cover, our products play essential roles across industries and applications.”

Andreas Gerstenberger, CEO of ContiTech USA and Head of Business Area Industrial Solutions Americas, said, “We are ready to lead in this segment. This new plant reflects our commitment to both innovation and proximity. With our customers increasingly looking for responsive and innovative solutions, we are proud to deliver with local production, advanced technology and a skilled workforce. More than just expanding our footprint, this investment is about creating mutual value with our customers, partnering closely to help them succeed in their own markets. By placing customer needs at the centre of everything we do, we aim to be their first choice for material-driven solutions, now and in the future.”

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