What is Carbon Black? Easy Guide to Basics

Carbon black is a pure black powder, and it has also been termed as carbon fume. It consists of elemental carbon, an amorphous form of carbon. The main material used as a base in many industries is carbon black. Insufficient air combustion of hydrocarbons produces carbon black. Unlike soot, carbon black does not contain any inorganic contamination and extractable organic residues.

Properties of Carbon Black

Carbon black can be considered the most widely used nanomaterial. It consists of microcrystalline structures with diameters from tens to hundreds of nanometres. The table below gives a complete overview of carbon black’s physico-chemical properties; it summarizes the main characteristics and the properties which are relevant in industries.

Particle Size

Size can be defined as the average diameter of carbon black particles, which typically consists of everything from 10 to 200 nanometers. Dimensions differ within various distributions of the particles and relate to different production processes and natures of raw materials.

Structure

Carbon black consists of primary “particles” or “nodules” that fuse into rigid colloidal entities called aggregates. These nodules consist of micro graphite stacks with their c-axis perpendicular to the surface.

Porosity

Carbon black pores are of two types: microporous and mesoporous. The former refers to less than 2nm in pore size, while the latter refers to pores between 2nm-50nm. Such pores in it raise the aging and abrasion resistance of the rubber.

Chemical composition

Carbon black’s main components are elemental carbon (>97%), hydrogen, oxygen, sulfur, and nitrogen.

Surface Chemistry

Oxygen functional groups (phenols, quinones, carboxyl groups) on the surface of carbon black affect its reactivity, dispersion, and electrical properties. Carbon black oxidation improves the dispersion of carbon black pigments while also lowering the pH and altering the sulfation kinetics.

Density

The density of carbon black lies between bulk density and actual density. Different types of carbon blacks have different packing densities. Among them, vulcanized and pyrolytic carbon black have higher packing densities, and gas-phase surface-treated carbon black has lower packing densities.

Color

Carbon black is generally divided into high-pigmented, medium-pigmented, ordinary-pigmented , and low-pigmented carbon black according to color strength and particle size. It has good dispersion performance, coloring power, and strong covering power.

Solubility

It has irreversible dissolution properties and is difficult to dissolve into liquid form. However, the actual carbon black is partially dissolved under some special conditions.

Heat Dissipation

Carbon black’s thermal dispersion affects rubber products’ mechanical properties, heat resistance, and oxidative stability. Mechanical mixing and wet or dry processing are typical methods for achieving carbon black dispersion. Dispersants, surface modifiers, and sophisticated processing methods frequently distribute it more evenly.

What Is Carbon Black Used for?

Tire and Rubber Industries

Carbon black is also a generic term for a major class of reinforcing products for rubber. Today, the world presently produces and consumes 70% of the world carbon black production supply for the rubber tire industry. Carbon black is added to tires in order to enhance the tire’s abrasion resistance, to improve the tire’s traction or grip on the ground, and to reinforce the tire for performance in durability and stability.

Plastics and Coatings

 Plastics

Carbon black is utilized in the following plastics: polyethylene, polypropylene, polyvinyl chloride, and polystyrene, improving such mechanical properties as tensile and abrasion resistance, giving electrical conductivity, and heat and weather resistance.

Coatings

It plays an important role in coatings for construction, automobiles, railroad cars, and ships. In general, coatings require the following properties: high blackness, good flow properties, and good stability against settling.

Conduction and Electronic Materials

The conductivity of carbon black is related to structure, surface, and particle size density, mainly through conductive channels and field emission mechanism.

EMI shielding

Conductivity can be realized by the composites of carbon black-polymer, mainly carbon black is used as the main raw material, adding certain fillers and adhesives. Due to the conductive, antistatic and electromagnetic interference-shielding qualities of it, the conductive carbon black can also be used in the producing of electromagnetic shielding materials.

Carbon black grades

By particle size, structure (such as surface area and DBPA values), and use properties, its grades are usually divided into the following categories:

How is carbon black made?

Furnace Black Carbon

It is derived from incomplete combustion of the raw material oil in a reactor.

Channel Black

It produced from natural gas has the advantages of tiny particles, big specific surface area, high blackness, and strong color power. More oxygen functional groups can delay the rubber vulcanization process to enhance the fluidity and printability of ink.

Thermal Black

It is mainly manufactured by high-temperature natural gas cracking under oxygen-free and flame-free conditions. The specific surface area of this carbon black is low, with low oxygen content on its surface.

What is the Carbon black price in the market?

Raw material costs

Carbon black mainly uses raw materials produced through coal tar. Recently, the fluctuating market price of coal tar has directly impacted production costs. In the month of March this year, for example, the price of coal tar surged up by 645USD/ton, driving up the cost of carbon black.

Market Supply and Demand Relationship

Therefore, at the beginning of 2024, carbon black manufacturers in Asia anticipated demand to increase significantly and thus increased production accordingly. However, it soon came into view that the actual procurement rate varied than what was estimated. This caused a supply overhang in the market. The market conditions have recently improved due to the end of the quarter, and the prices are henceforth stabilizing.

Carbon black vs Graphite

Chemical properties

Carbon Black chemical properties are relatively active, whereas graphite chemical properties depict stability, high temperature and corrosion resistance. Graphite shows non-soluble behavior in the case of water and organic solvents. At high temperatures it readily reacts with oxygen or metal and forms oxides or carbides respectively.

Physical Properties

Graphite has different chain or grape-like aggregation structures, and their major appearance is crystalline. Both Graphite and carbon black show a good electrical conductivity.

Optical Properties

Graphite is relatively homogeneous in terms of blackness and has a high light-scattering power and therefore cannot be used as an effective pigment. The blackness of carbon black mainly stems from its ability to absorb light; generally, the finer the particle size, the higher the blackness.

Carbon black environment impact

Energy consumption

The manufacturing process of carbon black involves the combustion of huge amounts of energy such as oil and natural gas. However, the overconsumption of power results in resource overutilization and greenhouse gas emission.

Air pollution

Carbon black production emits VOCs along with particulate matter, which are contributors to degraded air quality.

Substitution and Sustainability

Because of the nature of the carbon black creation process, there is the ability to utilize clean energy solar and wind in addition to incorporating used waste and alternative green materials.

Conclusion

Carbon black is an indispensable substance in the modern industry. Owing to its high coloring, high electrical conductivity, and good thermal dispersion, it has become highly important in rubber, plastics, coatings, inks, etc. Carbon black can meet the needs of different industries in relation to environmental pollution caused by production, and there is still a need to explore how to improve it.