materials feature | Polyolefins
effective and less energy intensive. The additives also enhance the mechanical properties and water-repellen- cy of the materials, says the company. To enable the separate components to bond
effectively – and to keep resistance in the process as low as possible – the additives are incorporated as lubricants. They contain a thermoplastic silicone elastomer. In comparison with conventional silicones – which cure irreversibly following vulcanization – ther- moplastic silicones behave thermoplastically within a certain temperature range. “A regular silicone wouldn’t melt under these
conditions – but ours does,” said Martin Schmid, senior marketing manager at Wacker Silicones. He says the company has developed the additives in
Wacker’s Genioplast silicone additives raise the manufac- turing efficien- cy of WPCs while boosting product quality
“With Baeropol RST there are no solubility issues,”
he said. The fact that the additives are generally regarded as
safe (‘GRAS’), they do not need approval in order to be used in new applications. Baeropol RST also forms the basis of the company’s
T-Blends, which incorporates traditional stabilisers to provide economical, stabilisation for technically demanding, price-sensitive reprocessing markets. Arne Schulle, CEO of Baerlocher, added: “This
technology development, based on our extensive experi- ence in oleochemistry, is launching us into a new business environment.”
Extending recyclates Imerys says that its ImerPlast additive boosts the performance of recycled polyolefins. ImerPlast is a compatibilised, mixed polymer compound consisting of recycled PE and PP resin, with a mineral-based compatibilising agent. It extends the number of useful applications of recycled plastic feedstock, allowing a higher recycling rate and increasing the scope of recycled polymers, says the company. The engineered mineral – which also overcomes phase separation and ensures stable production – is already being used in pipes for drains and sewers and for wood-plastic composite (WPC) decking. The product was seen at last year’s K2016 exhibition – as was the RP 17 additive from Struktol, a combination of lubricant and odour neutralising mask. It was originally designed for reducing or eliminating com- pounding and end-product odours in WPCs, and has now been modified for use in other recycling applications. At the same event, Wacker launched a range of thermoplastic silicone additives that raise the manufac- turing efficiency of WPCs. Its Genioplast WPC additives improve processing when extruding plastic blends that contain wood, to make manufacturing more cost
26 PIPE & PROFILE EXTRUSION | March 2017
masterbatch form. Tests show that 1% of the additive can increase throughput by 15-25% – depending on the plastic blend and extruder used. This leads to lower unit costs in production. In comparison, says Wacker, conventional lubricants require WPC manufacturers to use 2-6% of additive to achieve the same effect during extrusion. Genioplast WPC additives can be blended easily as the thermoplastic silicone elastomer is already premixed with the corresponding plastic. At present, formulations with PP (PP 20A08) and PE (HDPE 20A03) are available, but the company is also working on a PVC version. Wacker says that the additives lead to end products with higher impact strength and flexural toughness, as well as reduced water absorption. “The main market for this is the US, followed by China,” said Schmid. “Europe plays a smaller role.”
Silicone boost Other silicone additives are also helping the boost polyolefin performance. Dow Corning says that its MB25-502 masterbatch is a silicone technology designed to optimise the processability of highly mineral-filled polyethylene (PE) compounds for wire and cable applications. By reducing screw torque, die build-up and die pressure, the material can improve extrusion throughput by up to 110% compared to PE compounds without a processing additive, says the company. “The wire and cable industry is moving toward the
use of halogen-free flame retardants, but these mineral additives can cause major processing issues due to the high loadings that are required for effectiveness,” said Christophe Paulo, global segment leader for plastics and composites at Dow Corning. “Until now, customers were forced to choose between expensive, over-engi- neered additives with higher performance, or low-cost but underperforming products.”
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