CARBON BLACK is a finely broken form of amorphous carbon normally formed as soot from partial combustion of hydrocarbons under controlled conditions. Physically, the material is black in colour and is available in pellet or powder form. Carbon Black finds use in manufacturing of tyres, rubber products, printing inks, plastic products. IN terms of production levels, carbon black is amongst the top fifty industrial chemicals manufactured globally. About 80% of carbon black is used in making rubber products (including tyres).
Manufacturing Carbon Black
The furnace black process of manufacturing carbon black requires the use of heavy aromatic oils as feedstock. The furnace uses a reactor that is closed to allow the feedstock oil to ‘atomise’ under controlled temperature and pressure. The primary feedstock is passed via a hot gas stream allowing it vapourise and then pyrolyse in the vapor stage to form very minute particles. The reaction rate is controlled using either steam or water sprays. The carbon black so manufactured is passed through the reactor and on cooling collected in bag filters. The residual gas from the reactor consists of variety of gases: carbon monoxide & hydrogen. Natural gas is pushed into the hot furnace and the heat from the refractory material decomposes the natural gas into carbon black & hydrogen. The material stream is drenched by spraying water and filtered. Further the impurities are removed and the material is pelletized and packed.
Application
Carbon black finds used in the tyres as a reinforcing
agent. However, companies have started finding newer application for carbon
black such as for pigmentation, UV stabilization and conductive agents in various
other products.
- Rubber Products: Carbon black is included in a rubber product as (a) a filler and (b) a strengthening agent. In a tyre, carbon black is used for the inner-liners, carcasses, sidewalls and of course the treads. Other industrial use products such as gaskets, hoses, conveyor belts, bushings, bumpers, pads etc use carbon black.
- Plastic Products: Carbon black is also used in plastic packaging, moulded products, pipes, cables, industrial bags, etc.
- High Performance Coatings: Carbon blacks allows pigmentation, conductivity, and UV protection for coating applications in automobiles, aerospace, decorative, wood, and industrial coatings.
- Printing Inks: Carbon black is used in printing toners and inks.
Issues Concerning Carbon Black
- Carbon black is a tough customer to handle. It lumps
easily as well as fluidises easily. Manufacturers often complain of carbon
black deposits forming in the conveying line. The material is insoluble in water
and other solvents. Shop floor workers must ensure that the material does not spill
since cleaning the area becomes a time consuming and a difficult exercise where
dry vacuuming and filtration will have to be also resorted to. - Continued exposure to the material should be
avoided since (a) the inhalation of the carbon black dust can likely cause respiratory
issues and (b) coming in contact may impact the skin by causing it to dry. In some
research, the material has also suggested to be carcinogenic. - The material should be stored in a clean and dry
space and should not be exposed to heat, flames or other aromatic chemicals. Carbon
black has a tendency to absorb moisture and chemical vapours affecting its
properties.
