• 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.

 

Covestro India has entered into a strategic collaboration with CSIR-National Chemical Laboratory (NCL) through an innovative CSR initiative focused on developing sustainable upcycling technologies for polyurethane waste. This partnership aims to overcome existing recycling limitations by transforming discarded polyurethane materials into valuable chemical feedstocks, potentially revolutionising the material's circular economy.

This collaboration underscores both organisations' commitment to environmental innovation, leveraging NCL's advanced research infrastructure and Covestro's market leadership to address critical gaps in plastic circularity. Current polyurethane recycling methods, predominantly mechanical with some emerging chemical processes, face substantial challenges including material degradation, high energy consumption and hazardous byproduct generation. The project seeks to develop commercially viable chemical recycling solutions that maintain material integrity while minimising environmental impact.

Polyurethanes, widely used in furniture, automotive parts and insulation, present unique recycling difficulties due to their complex molecular structure. Most end up in landfills after use, creating significant sustainability challenges. By combining Covestro's industrial expertise with NCL's seven decades of chemical research excellence, the partnership aims to create breakthrough upcycling technologies.

Avinash Bagdi, Director & Head of Sales & MD Solutions India & Projects – Tailored Urethanes, said, "This partnership strengthens our commitment to finding innovative solutions for polyurethane waste and directly supports Covestro's vision of becoming fully circular. By developing effective methods to upcycle polyurethanes, we're taking concrete steps towards creating a more sustainable future in line with our corporate vision of driving the transition to a circular economy."

Dr Ashish Lele, Director of NCL, said, "CSIR-National Chemical Laboratory is excited to partner with Covestro (India) in this groundbreaking initiative to develop novel chemical upcycling methods for polyurethane waste. The conventional and electrochemical strategies we're developing address the critical limitations of current recycling technologies and align perfectly with our shared vision of a circular economy. This collaboration represents a significant step towards sustainable plastic management in India and globally, with potential to transform polyurethane waste into valuable chemical resources."

Zeon Corporation has begun building a pilot facility at its Tokuyama Plant in Shunan City, Yamaguchi Prefecture, to test a new method for efficiently producing butadiene from plant-derived ethanol. The demonstration plant, expected to start operations in 2026, will supply butadiene for manufacturing trial batches of polybutadiene rubber, bringing the company closer to commercialising this sustainable production process.

This project is a key part of a joint initiative between Zeon and The Yokohama Rubber Co., Ltd. to develop eco-friendly methods for producing butadiene and isoprene from renewable sources, with full-scale adoption targeted for the 2030s. Under the collaboration, Zeon will produce butadiene rubber at the new facility, while Yokohama Rubber will use the material to create experimental tyres and conduct performance testing. The data collected will help refine the technology ahead of larger-scale trials. The companies aim to finalise the production process by 2030 using an expanded pilot plant, with plans for industrial-scale commercialisation by 2034.

A ceremonial groundbreaking event took place on 10 July 2025, with 33 attendees, including local government officials from Yamaguchi Prefecture and Shunan City, construction partners and Zeon executives such as Chairman Kimiaki Tanaka and Tokuyama Plant Manager Akira Honma. The gathering included traditional safety prayers for the construction phase, marking the official start of this sustainability-focused industrial project.

Continental is increasing its use of renewable and recycled materials in tyre production, aiming to exceed 40 percent by 2030 while maintaining high safety and performance standards. In 2024, these materials accounted for 26 percent of tyre composition, with a projected 2-3 percent increase in 2025. Key to this shift are carbon black and silica – essential fillers that enhance durability, grip and braking performance.

Silica, a critical component for optimising grip and minimising rolling resistance, is traditionally derived from quartz sand. However, Continental now obtains silica from rice husks, an agricultural by-product of risotto rice production. This innovative approach not only repurposes waste but also requires less energy than conventional methods. Partnering with manufacturers like Solvay in Italy, Continental integrates rice husk-derived silica across its entire tyre portfolio. Silica has been a game-changer in tyre technology for decades, significantly improving safety and energy efficiency. Its use in tread compounds has contributed to a nearly 50 percent reduction in braking distances while also lowering rolling resistance, thereby reducing fuel consumption and CO₂ emissions.

Carbon black, another vital material making up to 20 percent of a passenger car tyre's weight, is being sourced through sustainable alternatives. Continental employs three innovative methods: bio-based carbon black from tall oil (a paper industry by-product), recycled carbon black from pyrolysis oil derived from end-of-life tyres and a direct recovery process that extracts carbon black from used tyres via pyrolysis. The company collaborates with suppliers like Orion Engineered Carbons and Tokai Carbon, utilising different carbon black variants tailored to specific tyre components, such as sidewalls and treads. Through the mass balance approach, Continental substitutes fossil-based raw materials with bio-based or recycled alternatives without altering existing production processes.

Additionally, Continental has partnered with Pyrum Innovations to advance tyre recycling through pyrolysis, a process that recovers carbon black from end-of-life tyres for reuse. While currently applied in forklift tyres, efforts are underway to adapt this recycled carbon black for broader tyre applications, ensuring compliance with performance and safety standards. These initiatives underscore Continental’s dedication to sustainable innovation, demonstrating how eco-friendly materials can enhance both tyre performance and environmental responsibility across the value chain.

Jorge Almeida, head of Sustainability at Continental Tire, said, “Innovation and sustainability go hand in hand at Continental. Using silica from the ashes of rice husks in our tyres shows that we are breaking completely new ground – without compromising on safety, quality or performance.”

Tata Motors-owned British-luxury brand Jaguar Land Rover is said to become the first global automaker to commit to use tyres made from renewable materials as part of its sustainability commitment.

The automaker will soon become the first to soon adopt tyres made from more than 70 percent renewable and recycled materials, such as silica from rice husks and plant‑based resins at scale in its upcoming range of vehicles.  In fact, the upcoming select models from Range Rover are already planned to come with Pirelli’s new P Zero tyres, which contain silica used to enhance wet performance. The material is sourced from rise husks, a natural by-product of rice milling.

These tyres do away with fossil‑based polymers and resins, which are typically used to help optimise the balance between dry and wet performance. Instead, they use plant‑based alternatives such as agricultural by‑products or used cooking oils. By using recycled materials, they reduce reliance on primary source materials to help alleviate resource consumption. Furthermore, carbon black, a crucial filler in rubber compounds used to improve stability, strength and durability, is recovered from end‑of‑life tyres and recycled steel is used to enhance handling and stability.

The automaker believes that bio‑based and recycled materials are generally more sustainable to obtain, more energy efficient to process and easier to manage at end‑of‑life than virgin and fossil‑based materials such as synthetic polymers and silica obtained from conventional materials such as quartz sand, yet perform similarly.

Reuben Chorley, Sustainable Industrial Operations Director, Jaguar Land Rover, said, “This is another example of how JLR is leading on sustainable design innovation in collaboration with its supply chain partners to deliver at scale, while reducing the environmental impact of our products. Achieving a more sustainable composition without compromising quality and performance is a challenge because of the complexity of tyre design. But working closely with Pirelli and leveraging both company’s expertise in procurement and engineering, we have been able to deliver this industry first.”
JLR and Pirelli are strengthening their commitment to sustainability with the introduction of the new P Zero tyre, featuring FSC (Forest Stewardship Council)-certified natural rubber. This initiative builds on JLR's pioneering move last year to incorporate FSC-certified natural rubber across its entire vehicle portfolio, ensuring responsible sourcing within its supply chain.

Both companies are dedicated to increasing the use of recycled and bio-based materials in their products. All such materials will undergo third-party certification to verify their quality and quantity. The long-term ambition for JLR and Pirelli is to achieve 100 percent sustainable materials in their tyres.