MATERIALS | CARBON BLACK


shear resistance compared with Ensaco 250G. Caprara says this means that in compounding operations involving high shear forces (for example, when manufacturing concentrates or when working with highly viscous polymers) the structure is less affected, leading to better conductive properties. Another advantage lies in its higher specific


Figure 2: Volume resistivity of a range of Unipetrol Chezacarb AC polymer compounds as a function of carbon black content (extruded sheets)


Source: Unipetrol


for electrotechnical, automotive and packaging market segments,” says Semenyšínová. Chezacarb AC and Macroplus CC are both used to obtain permanently antistatic, dissipative or electro-conductive materials (Figure 2). Typical application market segments include extruded profiles, pipes, sheets, blown film and injection moulded parts. Semenyšínová adds that further Chezacarb AC developments aimed at new application areas including 3D printing systems, as well as paints and coatings, are scheduled for introduction around the middle of next year.


Specialty focus Imerys Graphite & Carbon is continuing with its investment strategy focused on fuelling growth in specialties. Benedetta Caprara, Market Leader Europe, reports that demand for electrically conductive products continues to increase and says that the company’s Ensaco carbon blacks “are the ideal solution when high purity, excellent dispersion level or low moisture are required.” Caprara cites its Ensaco 250G as one


Right: Imerys Graphite & Carbon is targeting specialty conductive applications with its Ensaco blacks


example, describing it as “the cutting-edge solution, with a winning combination of high structure and low surface area, which guarantees an excellent dispersion of conductive carbon black in plastics.” This good disper- sion means polymers show good retention of mechani- cal and flow properties. Another product of interest for plastics applications is Ensaco 260G. Its main advantage is its higher


32 COMPOUNDING WORLD | November 2017


aggregate conductivity. This enables highly conductive compounds to be manufactured with advantages such as better EMI shielding proper- ties. It also enables recipe developers to target a specific conductivity using slightly lower amounts of carbon black, which provides benefits in terms of viscosity and impact properties (Figure 3). At Cabot Corporation, Global Segment Manager George Haines highlights the very high purity levels of several of the company’s carbon blacks. He points to a food contact notification (FCN 1789) approved by the US Food & Drug Administration (FDA) that overrides 21 CFR 178.3297 with regard to Cabot’s high purity furnace blacks (Black Pearls 4750, Monarch 4750, and Black Pearls 4350). “Previously, there was a limit of 2.5% by weight in the polymer, but as stated in the FCN, the limit has been changed to the minimum required to accomplish the intended technical effect,” he says. “This means our customers can exceed the previous 2.5% if needed [and] demonstrates Cabot’s continued leadership in high purity carbon blacks as FDA has granted this approved use only for Cabot’s high purity grades.” Cabot is also expanding furnace carbon black


applications to enable an up to 20% improvement in insulation performance for expanded polystyrene (EPS) foams. “Through our CSX691 carbon black and Plasblak PS6310 black masterbatch, we are helping end-users meet energy efficiency targets and expanding the additive options available to improve insulation performance,” he says.


PHOTO: IMERYS GRAPHITE & CARBON


Challenging applications Ranjan Kamat, Applications Manager-Plastics at Birla Carbon Specialty Blacks, says that the use of carbon blacks in conductive compounds is one of the most challenging applica- tions in terms of selection


of the appropriate com- pounding equipment and processing conditions. Birla


Carbon offers its Conductex series www.compoundingworld.com


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