technology | Wire and cable In PE compounds with high mineral loadings (up to


70% by weight), the new masterbatch can reduce screw torque by as much as 30%, raising output and cutting energy costs. It is also said to avoid die build-up. The product is more effective at lower loadings (0.5 to 1.0%) than competitive silicone-based additives, the company claims, and is compatible with low and linear low density PE and cross-linked PE (XLPE). Discussing the company’s product range at the


Cables 2017 conference (organised by AMI in Cologne in March) Michal Hrebiˇ


cík, Technical Support and


Figure 1: Output rate at various torque values for a reference PE cable compound with and without Dow Corning’s MB25-502 silicone additive Source: Dow Corning


Development Specialist for Dow Corning in Poland, said that mineral additives also cause: lower surface lubricity, making it more challenging to pull wires and cables through conduits; higher water absorption, which affects electrical insulation; and poor mechanical properties. He said a number of different silicone-based additives are available to tackle these problems. New developments in silicones were the subject of


Images showing the effects of various additives on die drool of a 65% ATH/ MDH (alumina trihydrate/ magnesium hydroxide) filled HFFR cable compound


Source: Dow Corning


several presentations at the Cables 2017 conference, with speakers from Evonik, Wacker and Elkem also addressing the topic. Kathrin Lehmann, Head of Innovation Management for Polymers at Evonik, discussed organo-modified siloxanes (OMS) in halogen- free flame retardant (HFFR) compounds. She said that the company’s Tegopren products, for example, can be used as a surface treatment on magnesium hydroxide(MDH) to make it hydrophobic, providing benefits in improved dispersion, improved electrical insulation properties, better flame retardance, and smoother surfaces. Wacker Chemie offers its Genioplast additives for


improved processing, flow, and property enhancement of cable compounds. Genioplast Pellet S, for example, is made from silicone gum (polydimethylsiloxane) containing HDK pyrogenic silica nano-scale aggregates. Senior Technical Manager Michael Geck said at the AMI conference that improvement of processing, flow, surface and mechanical properties of HFFR cable compounds is mainly due to the silicone gum constitu- ent of Genioplast Pellet S, while the silica constituent provides a low peak heat release rate, a stable and compact char and low smoke release. Elkem’s Sidistar is an amorphous silica with a mean


The effect of Evonik’s Tegomer V-Si 4042 organo-modified siloxane on heat release rate of EVA containing mineral-based flame retardant Source: Evonik


18 COMPOUNDING WORLD | May 2017


particle size of 150nm and no aggregate structure, distinguishing it from precipitated and fumed silicas. At Cables 2017, the company’s Polymer Additives Business Manager Richard van Sprang explained how it can be used as a partial (50%) replacement for antimony trioxide (ATO) in PVC cable compounds without any significant effect on heat release rate, providing cost savings of around 12% on a volume basis. The driver for such a move is the price of ATO, which he pointed out


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