Carbon Black is a form of amorphous carbon that has high surface area to volume ratio; which essentially consists of elemental carbon in the form of near spherical particles of colloidal size coalesced into particle aggregates and agglomerates and are obtained by the partial combustion or thermal decomposition of hydrocarbons. Carbon black is also in the top 50 industrial chemicals manufactured worldwide, based on quantity.
Carbon black is used in rubber as a reinforcing agent and in plastics, printing inks, coatings, sealants, and a variety of other products for pigmentation, electrical conductivity, rheology control and UV protection.
It is the ability of carbon black to enhance the mechanical properties of elastomers, such as tensile strength and abrasion resistance or wear resistance and is widely used in tyre and rubber products. Rubber reinforcement occurs when the long strands of rubber molecules are able to attach themselves to the carbon particles, which have been mixed into the rubber compound. The rubber molecules previously intertwined but not attached to each other, are no longer able to slide past each other easily due to multiple carbon black attachment.
Carbon black is a superior opacifier for a wide range of applications. This characteristic stems from the ability of carbon black to absorb radiation across the spectrum of visible light. This excellent absorbing ability allows strong reductions in transmitted and reflected light.
How does carbon black impart electrical conductivity to polymeric systems? Carbon black is more conductive than polymers, resins, or rubber. Addition of carbon black reduces the electrical resistivity by forming a conductive network through the polymeric matrix. Grades of carbon black have been developed to optimize conductivity at lower loadings while meeting all other critical performance requirements for conductive applications.
The four main factors that influence the UV protection of a plastic compound are: carbon black particle size, structure, dispersion quality in the plastic matrix, and its loading in the plastic formulation.
Silica is also used as filler somewhat a substitute for carbon black. But it is a challenge to acquire improved and stable polymer-filler network.
Yes, there are different grades of carbon blacks.
Carbon black properties, such as color, degree of rubber reinforcement, or ease of dispersion, are tailored to suit specific applications. The selection of the grade of carbon black for different applications is primarily based on the surface area and structure, and in some special applications on the surface activity or surface modifications of chemical groups on the surface of carbon black.
Codes like ‘N326’ or ‘N###’ are general classifications for carbon black grades as per D24 – ASTM Committee. Most of the grades of N100 series, N200 series, N300 series, N500 series, N600 series and N700 series are produced by PCBL.
These general classifications do not give information on the purity, cleanliness or analytical consistency. These specific attributes are available in PCBL carbon black grades. We have carbon black equivalents for all such grades, many of which are provided in both fluffy and pelleted form.
Pelletized blacks are easier to store, handle and convey than fluffy products. Fly-loss during handling and housekeeping problem will be less in pelletized blacks as these are less dusty. Pelletized grades are sometimes more difficult to disperse in comparison with their corresponding fluffy grades. The decision to use fluffy black is generally made because available equipment is inadequate to disperse pellets.
Higher structure carbon blacks are generally more easily dispersed than low structure carbon blacks of similar surface area. A high structure carbon black is one in which the aggregates are composed of many primary particles clustered together with considerable branching and chaining. As a result, the aggregates pack more poorly reducing the inter-aggregate attractive forces. Low structure carbon blacks are more compact, allowing closer packing and thus greater inter-aggregate attractive forces which makes dispersion difficult. However, while an increased supply of energy is required to disperse lower structure carbon blacks, their higher density allows them to ‘wet’ or incorporate easily due to less occluded air to displace.
Some grades of carbon black are post treated to increase the amount of chemisorbed oxygen on their surfaces. In some end use applications, this improves the rate of dispersion by improving the rate of wetting. Dispersion stability of the carbon black also increases and product viscosity is reduced.
Undertone relates to a secondary colour property of carbon black. Depending on the size of the primary particle and its level of dispersion, both of which influence light absorption (jetness) and scattering (undertone) characteristics, resulting in either a brown or a blue undertone.
Pelletized blacks are easier to store, handle and convey than fluffy products. Fly-loss during handling and thereby housekeeping problem will be less in pelletized blacks as these are less dusty. Pelletized grades are sometimes more difficult to disperse in comparison with their corresponding fluffy grades. Pellets are also less expensive than the corresponding fluffy carbon black. The decision to use fluffy black is generally made because the available equipment is inadequate to disperse pellets.