additives | Carbon black
Conductive compounds produced on a twin screw extruder using split feeding will display higher conductivities than single feeding, where solid-solid contact reduces the carbon black structure, says Imerys
with the new EU regulation. George Haines, global segment manager at Cabot,
says: “We believe that we now offer the broadest range of specialty carbon blacks that are certifi ed to facilitate compliance with the new REACH requirements. We have been a leader in providing high purity carbon blacks, including those used in applications that need to comply with EU food contact legislation requirements. “Further, we are now taking steps to certify carbon blacks that enable customers to meet the updated GS Mark requirements. This work around PAHs builds on Cabot’s leadership with high purity furnace blacks used in applications that need to meet the strict require- ments laid out by the US FDA (21 CFR 178.3297).” Omsk Carbon Group is another supplier highlighting
its research on solutions to reduce PAH content in its carbon blacks. “PAHs are diffi cult to remove from the surface. Nevertheless, under vigorous conditions PAHs
can be extracted and identifi ed using instrumental procedures. The use of post-reactor technologies is one of the methods to reduce PAH content in carbon black,” says Andrey Petin, director at the company’s R&D Center for Carbon Materials.
“For our preliminary research, we used a pilot reactor, which enabled us to conduct tests on smaller scales. As a result of industrial testing, we managed to reduce the total content of restricted PAHs to less than 20 ppm, and reduce the benzo[a]pyrene content to less than 0.25 ppm. Such PAH level is considered carcino- genically safe and makes it possible to use carbon black to produce critical items with regard to safety,” he says. Petin says this work helped the company launch a new range of grades with reduced PAH content. These include Omcarb CH85, N220FA and S500FA.
He also cites work that Omsk Carbon Group has
carried out in partnership with major (unidentifi ed) masterbatch manufacturers to develop new grades of carbon black for plastic pipes which come into contact with drinking water. The program is aimed at improving resistance to UV exposure and ensuring organoleptic properties stability and product chemical purity, “which enables the use of carbon black in articles that come into contact with foodstuffs and human skin.”
Conductivity issues At Imerys Graphite & Carbon, global polymer technical leader Christine Van Bellingen says the company’s Ensaco conductive carbon blacks “match the severest purity requirements, including for low PAH/BAP.” Imerys has been carrying out work to better
understand and improve the effectiveness of carbon black as an electrically conductive additive in plastics
New PAH restrictions in force in Europe
EU Regulation 1272/2013 provides several amendments to Regulation 1907/2006 governing polycyclic aromatic hydrocarbons, PAHs in certain polymeric products. They come into force on 27 December 2015. Among the amendments are these two paragraphs: Articles shall not be placed on the
market for supply to the general public, if any of their rubber or plastic components that come into direct as well as prolonged or short-term repetitive contact with the human skin or the oral cavity, under normal or reasonably foreseeable conditions of use, contain more than 1
28 COMPOUNDING WORLD | November 2015
mg/kg (1 ppm) of any of the [8] listed PAHs. Such articles include amongst others: sport equipment such as bicycles, golf clubs, racquets; household utensils, trolleys, walking frames; tools for
domestic use; clothing, footwear, gloves and sportswear; watch-straps, wrist- bands, masks, head-bands. Toys, including activity toys, and
childcare articles, shall not be placed on the market, if any of their rubber or plastic components that come into direct as well as prolonged or short-term repetitive contact with the human skin or the oral cavity, under normal or reason- ably foreseeable conditions of use, contain more than 0.5 mg/kg (0.5 ppm) of any of the listed [8] PAHs. The full regulation can be viewed as a
pdf here.
www.compoundingworld.com
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