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Antistats and conductive additives | materials feature


Lilli Sherman looks at the latest developments in conductive and antistatic compounds


Putting a stop to static and sparks


Global demand for electrically-conductive compounds is expanding strongly with global annual growth rates estimated at more than 5%. Key drivers for this growth include evolving safety standards and new technologies. Christine Van Bellingen, product manager at Timcal


Graphite and Carbon, says that growing markets include electronic packaging, power cable, automotive fuel systems and industrial equipment that needs to meet the expanding implementation of ATEX norms. The polymers being used in these areas include PC,


PS, HIPS and PP for electronic packaging products such as carrier tapes, carrier trays and films. Medium- and high-voltage power cables feature semi-conductive screens made of EEA, EBA and PE resins. In automotive fuel systems, resins such as HDPE, PA


and POM are used in fuel lines, pumps and filler necks that need to meet the SAE J1645 norm to reduce the risk of dangerous sparks. Similarly, industrial equip- ment used in potentially explosive environments such as mines and chemical plants needs to meet the ATEX norm, which has been expanding beyond Europe. This typically impacts on PA and other engineering plastics used in dynamic devices such as fans, transport hoses and motors. On the technology front, there has been growing interest in using carbon nanotubes (CNTs) to impart


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electrical conductivity to plastics. The major suppliers, including Arkema, Bayer MaterialScience, CNano, Nanocyl and Showa Denko, have scaled up production capacity significantly over the past few years. This has led to reductions in price by as much as a


third, according to Neil Hardwick, marketing manager for conductive compounds at RTP. He adds that the timing of the global expansion coincided with the global economic downturn and has resulted in excess capacity. RTP has focused on upgrading its CNT compounds


manufacturing capabilities, both in terms of capacity and processing. “CNTs process differently, so we have aimed to improve the consistency of CNT-filled compounds we produce. We have focused on how to disperse CNTs more evenly in a compound and how to optimize loading levels,” says Hardwick. Although CNTs are generating interest in this


market, carbon-black-filled compounds continue to account for the major portion of conductive plastics applications. They offer significant cost-performance advantages for many products. Developments in specialty conductive blacks have been designed to counteract the adverse impact that traditional carbon blacks can have on a polymer’s mechanical properties. “There is still a nice future for traditional conductive additives like conductive carbon blacks,” says Van


May 2012 | COMPOUNDING WORLD 37


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