Carbon Black

Carbon black is an industrial filler and part of the black pigment series. This material is produced industrially and through controlled processes of incomplete combustion or thermal decomposition of hydrocarbons (heavy petroleum products such as coal tar, FCC tar, etc.).  As a result, it is also called industrial soot.

Composition and Properties of Carbon Black

Carbon black or industrial soot absorbs white light and reflects a small amount of it. Over 97% of this industrial material is composed of carbon and the rest is hydrogen, nitrogen, oxygen and sulfur.

This substance absorbs ultraviolet radiation (UV), has elastic and abrasion features, and exists in very small particles. Due to these features, it is used in manufacturing of coatings, paints, ink, toner and as a reinforcing filler in producing plastic, rubber and polymer products. In high temperature, around 3000 degrees Celsius, this material is transformed into graphite. The smaller the carbon particles, the more profound and darker the color will be; On the other hand, the larger the particles, the lighter and brighter the color will become. Moreover, the conductivity of this substance is increased as particles become smaller.

Various Industrial Methods of Producing Carbon Black

There are different methods and processes for manufacturing this material. These methods are divided in two groups of Thermal Decomposition Processes and Thermal Oxidation Processes.

• Furnace Black Process

  The most popular and most important method for manufacturing carbon black is the furnace black process. In this method, furnace grade carbon black is produced by partial combustion of liquid, oil or gaseous petroleum derivatives in a closed furnace (refractory furnace). The surface of furnace soot is neutral.

  In the past, carbon black was solely produced through partial combustion of gas inside the furnace. This type of soot, was only applied in rubber industry. In recent methods, oil is combusted instead of gas, and various grades of soot can be produced by controlling the conditions. These products are used in different industries including paint, ink, rubber and plastic manufacturing. This method, in addition to safety advantages, possesses various benefits for the environment. Since the process is closed, the diffusion of gases, dust and pollutants are significantly reduced. Due to the availability of crude oil primary products and the possibility of better controlling the variables in this method, together with high efficiency and high production levels, furnace black has become the most important method for manufacturing carbon black.

• Channel Black Process

  Channel grade carbon black is derived from partial combustion of natural and gaseous hydrocarbons and the sedimentation of the fume of the flame over metallic and iron channels. The deposited layers, are chipped off from the surface of channels by using chipping blades. This type of soot is more acidic compared to other grades of carbon black. The resulting soot is very soft and fuzzy due to the existence of air and secondary gaseous products that are isolated inside the soot. Therefore, it should be put under pressure in order to derive the balled soot.

  In this method, the quality of soot can be monitored through adjusting the distance between the flame and the channel surface, the shape of flame, quality of gas and the amount of airflow. However, the efficiency of producing industrial soot through this method is very low. The substance derived in this method has much lower softness compared to the furnace black method. High cost of using gas, together with low efficiency has led to reduced share of this method in manufacturing carbon black.

• Gas Black Process

  This process is similar to the channel black process. Compared to other parts of the world, natural gas resources in European continent is much more limited. Therefore, the gas black method was developed by Degussa in 1995 by distillation of coal tar instead of natural gas. This method has far less negative impacts on the environment compared to the channel black process. Oil can also be used in this method as an alternative to natural gas in the channel black method.

• Lamp Black Process

  The lamp black process is one of the oldest methods for manufacturing this substance, used even before the birth of Jesus Christ. In this approach, which was improved over time, coal tar is produced in wide cast iron trays and tubs by burning oil in the furnace. Presently, most of the carbon black produced in this method is applied in rubber and plastic industries.

• Thermal Black Process

  Thermal grade carbon black is produced through contact of hydrocarbons with hot pipes in the absence of air. This method has lower efficiency compared to channel and furnace processes. Its product has larger particles, much lower coloring capacity and its surface is inactive. It also has lower oil absorption capacity, and is often used as a cheap filler in pastes and linings.

• Acetylene Black Process

  In this approach, carbon black and hydrogen are produced at 800°C by thermal decomposition of acetylene in refractory furnaces. The product has high conductivity. Production efficiency is very low in this method. Acetylene soot has high oil absorption and therefore has more limited application than other similar products.

  In general, chemical and physical qualities vary in industrial soot produced in each process. The shorter the burning time and the higher the temperature, the smaller the size of particles and the higher the coloring quality of the product will become.

Various Applications of Carbon Black

• Rubber Industry

  The most important usage of this substance throughout the world is as a reinforcing filler in automotive tire industry. The advantage of using carbon black is that it conducts away the heat faster, increases abrasion resistance, improves flexibility and resistance towards tear and therefore increases the longevity of tires. This material is also used in manufacturing rubber equipment including belts, hoses, sealing systems, washers, etc.

• Plastic Industry

  Carbon black is used in plastic industry for coloring, covering and protecting the product against heat and UV radiation. High abrasion and elastic features of this substance leads to enhanced quality and resistance of plastic products. It is also used in manufacturing heat conductive packaging, pipes, garbage bags, plastic molds, compact containers and many other home appliances.

• Ink Production Industry

  Carbon black is widely used as black pigment agent in manufacturing ink. It is also used for producing toners for printers and copy machines. Using carbon black enhances the viscosity of the ink and in turn the quality of printing.

• Paint and Coating Industry

  Industrial soot is widely used in producing various types of coating color products. This black pigment enhances the coloring and covering capacity of the paint. Moreover, industrial soot protects against the negative impacts of UV radiation. Due to these features, paints made with this pigment are used in aerospace, marine, automotive, and decorative industries and all sorts of industrial coverings.

• Polymer Industry

  Using this substance in polymer industry leads to sintering of its particles. This problem is solved by adding dispersion agent.

  This industrial soot is mainly used in polymer industry as masterbatch. Its application increases the resistance of polymer products against UV radiation. In this industry, this substance is mainly used in polymer covers of cables and wires. It is also applied for enhancing the quality of polystyrene insulations.

• Electrical Industry

  Carbon black is used in manufacturing conductive and electrical equipment.

• Packaging Industry

  In some countries, carbon Black is used in food packaging, including UTF bottles, meat packing, etc, to increase the longevity of food products. It is also applied in microwave trays.

• Construction Materials Industry

  Carbon black is used as pigment agent in manufacturing cement and colored concrete. The high conductivity of this substance leads to its wide application in producing heat conductive materials.

• Paper Industry

  This black pigment is used for producing decorative papers, colored papers and photo protector sheets.