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Carbon black usage to sustainable opportunities

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Disruptions to Carbon Black supply chains, rising costs of the fossil fuels used to produce Carbon Black, sustainability regulations, and stakeholder pressure have concerned industry leaders about the future of Carbon Black.

Luckily, more circular options are on the market, with similar properties to Carbon Black. Although they’re not directly replacing Carbon Black, these sustainable options have applications in many industries.

This article will teach you about the many recovered Carbon Black uses as a sustainable opportunity, especially as a feedstock for paints and inks.

What is recovered Carbon Black?

Recovered Carbon Black (rCB) is a solid residue from end-of-life tire (ELT) pyrolysis. Though rCB can be produced from various rubber waste, the billions of ELTs discarded annually provide a plentiful feedstock that would otherwise be treated as waste and end up in landfills.

Char is one of the tire pyrolysis products that is processed, milled, and pelletised to yield rCB. Industries manufacturing tires, inks, paints, coatings, and rubber that usually use virgin Carbon Blacks (vCBs) are opting for rCB. These industries find rCB is a sustainable choice capable of matching vCB properties and can help to overcome vCB supply bottlenecks and high costs. It’s also a more planet-conscious option that can meet consumer and industry demands for green products.

For example, the automotive industry is sourcing products made from recycled raw materials to make circular cars. Tire manufacturers incorporating rCBs into their tires can ensure that new cars are more sustainable and have a lower carbon footprint.

Similarly, the paints and coatings industries are adopting green chemistry and emphasising resource conservation by using products from alternate feedstocks instead of fossil fuels to minimise carbon emissions. Currently, 2 per cent of global fossil fuels are used to make ingredients for the paints and coatings industry.

Depletion of fossil fuels and concern over carbon emissions are driving the paints, inks, and coatings industries to look for sustainable opportunities. Instead of fossil fuels, rCB production uses ELTs as feedstock in pyrolysis, making rCB a circular option for vCBs made from fossil fuels.  

Properties: recovered Carbon Black vs virgin Carbon Black

Despite its environmental and cost advantages, rCB is not a 1:1 replacement for any particular vCB grade.

rCB is a new, unique grade with its own properties. The American Society for Testing and Materials (ASTM) International workgroup 36, set up in 2017, is still developing quality standards for rCB. The properties of rCB include a mix of passenger and truck ELTs used in pyrolysis. Recovered Carbon black’s in-rubber properties are close to the vCB grades from N550 to N772, with N650 and N660 as the closest matches, found in significant quantities in tires of all vehicles. In coatings or plastics, rCB can substitute popular grades like N220 and N330.

However, minor amounts of high reinforcing vCB grades in tire components will also be part of rCB. Moreover, the chemicals and additives in waste tires will also make their way into rCB, affecting its properties.

The circular option: Recovered Carbon Black

rCB is a sustainable Carbon Black option because of its small carbon footprint and circularity.Contec’s rCB manufacturing process ensures 80 per cent less or 2 tonnes fewer carbon emissions per tonne of the product than vCB production. Whereas producing vCB requires 2 tonnes of sulphur-rich fossil fuels, 1 tonne of rCB can be made from just three ELTs. 

The rCB’s low carbon footprint and circularity help industries comply with the environmental standards industries must now meet.

Tire producers can solve their waste problems and meet requirements set by the EU End-of-life Vehicles Directive using pyrolytic products.

The paints, inks, and coatings industries will find rCB valuable in reducing emissions as required by the Industrial Emissions Directive 2 2010/75/EU (IED) and its 2022 revisions covering chemicals production. The Directive regulates pollutant emissions (including greenhouse gases) and stipulates the use of Best Available Techniques to choose raw materials. The 2022 Commission to revise the IED supports improving resource use to build a low-carbon, clean, and circular economy.

Moreover, rCB’s low volatile organic carbon content and water-based formulations help the paints, inks, and coatings industries comply with REACH Regulation (EC 1907/2006) controlling the production and use of chemicals.

How is recovered Carbon Black made?

Around 20 to 30 types of pyrolysis processes exist, but not all are created equal. Conventional pyrolysis systems can’t guarantee consistency in the quality of rCB. Contec has improved the pyrolysis process with several innovations to make rCB of consistent quality.

What is pyrolysis? It’s a thermo-chemical process, and the technique is several decades old. While it has been used to recycle tire waste to recover materials for many years, market interest in the technology is new.

The tire rubber is separated from other components like steel, wires, and fabrics as part of the process and sent into a reactor. Contec uses its novel Molten technology to heat the shredded tires to temperatures up to 510°C in an oxygen-free atmosphere to decompose the complex polymers in tires into simpler components. The pyrolytic products of commercial interest are recovered gas, oil, Carbon Black, and steel.

What are common Carbon Black grades?

Carbon Black is a synthetic material made of 98 per cent carbon. Petroleum oil, gas, and coal tar are the common raw ingredients used to produce vCB through burning in reactors at very high temperatures to vaporise the carbon. After cooling, a paracrystalline spherical powder is made.

Different manufacturing processes and feedstocks produce varying particle sizes, surface area, and aggregate structure, which define the properties of the vCB. This means there are many grades of Carbon Black.

Most vCB grades stabilise and strengthen rubber products, but some also act as pigments:

  • Grades with smaller particles, such as N110, N220, and N234, have high reinforcing, abrasion resistance, and tear strength. These grades are used as reinforcing filler materials to make rubber elastomers that form tire treads.
  • Medium to high reinforcing grades like N330, N339, and N550 are found in tire treads, inner liners, carcasses, sidewalls, hoses, and extruded goods.
  • Medium reinforcing vCB grades like N660 and N770 have low heat build-up and prevent tire deformation. They’re suitable for tire sidewalls, inner liners, and sealing rings. Other applications include hoses, extruded goods, cable jackets, footwear, floor mats, and mechanical goods.
  • Low reinforcing vCBs like N990 have high loading capacity and elongation and are suitable for tire inner liners and belts, footwear, belts, hoses, mechanical goods, and wire insulation.

What are the uses of Carbon Black?

The tire industry consumes around 70 per cent of Carbon Black. Manufacturing other rubber products consumes around 20 per cent, with the remaining 10 per cent used for non-rubber applications. Carbon Black is used in many industries due to its potential uses as fillers, pigments, or UV protectants. 

1. Fillers

Tire manufacturing uses most vCB grades as fillers to stabilise and strengthen rubber products, such as tire treads, sidewalls, tubes, belts, and carcasses. The cumulative effect of vCBs makes tires safer, longer lasting, and more durable for driving.

The vCBs comprise 21.5 per cent and 22 per cent of passenger and truck tires, respectively. The rCB’s properties make it a suitable replacement for several of these vCB fillers, reducing the carbon footprint significantly.

2. Pigments and For UV-Protection

Several vCB grades produce a wide range of pigments with good tinting, conductivity, and dispersibility properties, providing ultraviolet (UV) protection.

  • The tire industry uses Carbon Black to protect tires from the harmful effects of UV light and ozone to extend tire lifespan. 
  • Inks, coatings, and paint manufacturers use Carbon Black to enhance the undertone and colour in many ink types, including toners for laser printers and screen inks. Coatings benefit from the Carbon Black’s high jetness, UV protection, and conductivity. High-performance coatings for aerospace, marine, wood, industrial, and decorative applications rely on Carbon Blacks.
  • Plastic manufacturers add Carbon Black to industrial bags, refuse sacks, and household containers. The Carbon Black adds colour and provides UV protection to the plastic polymers making them thermal resistant. These properties are also essential for power cable insulations.

The use of fossil fuels to provide feedstock and energy for the manufacture of vCBs has increasingly become an image and compliance issue in all industries. rCB is a sustainable option to vCB for several of the above applications. Adding 10 to 30 per cent of rCB will often maintain the properties while reducing the negative environmental impact.

Common recovered circular products from ELTs

Each of these four recovered products has a place in the circular economy.

1. Recovered Carbon Black

Contec’s ConBlack® is a sustainable Carbon Black option, which can replace up to 30 per cent of semi-reinforcing vCBs, such as N550 and N660, to make new tires. ConBlack® can make inner liners, sidewalls, sealing rings, heavy-duty conveyors, transmission belts, and hoses. Adding up to 100 per cent of rCB can secure UV protection and produce non-tire items like rubber sheeting, roofing, cables, geomembranes, pigments, paints, inks, coatings, and plastic items.

2. Recovered gas

Gas is one of the first products formed in pyrolysis. Some condense into liquids during cooling, but the rest remains as gas, rich in hydrocarbons such as methane, butadiene, and butadiene. Contec has achieved self-sufficiency by using its recovered gas to heat the Szczecin plant.

3. Recovered Oil

Contec’s ConPyro® is the oil produced after refining and can equal virgin fossil fuels in quality. Sulphur and aromatic hydrocarbon-rich end-of-life tires derived pyrolysis oil (TDO) can replace fossil-based oil as feedstocks to produce high-reinforcing vCBs. These vCBs can further increase the proportion of recovered materials in tires.

4. Recovered steel

Contec’s ConWire® is retrieved before and after pyrolysis and can also be used again to produce new tires without losing quality. The tire, paints, coatings, ink, and plastic industries are considering various options, including biological materials and recycled products, as circular options to produce more sustainable Carbon Black options.

Manufacturers should consider using recovered Carbon Black

Recovered Carbon Black’s importance as a sustainable, circular raw material for several industries is growing.

In the tire manufacturing industry, rCB can offer a greener option. In the inks and paints industries, higher concentrations of rCB will be required to get the same pigment opacity levels as with vCB. However, the environmental benefits of rCB are considerable and outweigh the issues associated with making the switch.

Contec’s ConBlack® uses ELTs as feedstock and is asustainable and circular Carbon Black option to vCB because of its various proven uses and applications in several industries, from tire and rubber to paints, coatings, and inks. Get in touch to learn more about our sustainable solutions.

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