COMPOUNDS | ELECTRICALLY CONDUCTIVE


BASF’s Elastostat antistatic masterbatches can achieve surface resistivity levels of 108-109 Ohm Source: BASF


ment the current 300µm range, Procotex is now also developing granulates with a carbon fibre length of 1mm to offer even higher conductivity and improved reinforcing capacity along with accurate, dust-free handling and high filler dispersibility,” he says. With the automotive industry in mind, Procotex also plans to offer carbon fibre products with a sizing developed specifically for a polypropylene matrix. “Initial study results not only show increased stiffness, strength and electrical conductivity of the reinforced materials, but also highlight the remarkable retention of low-temperature impact performance,” Miltner says.


Polymeric antistats As already demonstrated, there are numerous ways to achieve antistatic properties in compounds and it is not always through the use of particulate addi- tives. An alternative option involves addition of ther- moplastic elastomers such as the Pebax polymers from Arkema. These thermoplastic elastomers comprise a hard polyamide segment and a soft polyether segment. Grades for antistatic modifica- tion use a polyether that is hydrophilic — picks up water — which increases its electrical conductivity. Traditional Pebax grades are made with a hard segment in PA6 or PA12. A new antistatic grade, however, contains PA11 sourced from castor plants, making it partially (41%) bio-based. It was intro- duced at the Conductive Plastics 2019 conference organised by Compounding World publisher AMI last October in Vienna. The new Pebax RNew 30R51 grade is suitable for use in biobased polymers such as PLA, says Market Development Manager Clio Cocquet. It also has the extra benefit that its refractive index has been tuned so it can be used in acrylic (PMMA) without affecting transparency. Typical applications include cosmetic packaging, furniture and lighting, where the additive helps reduce the attraction of parts to dust. Arkema is currently ramping up capacity for


48 COMPOUNDING WORLD | February 2020


bio-PA11. It is building a world-scale bio-based production plant in Asia, which will provide it with substantial extra capacity for making the new antistatic Pebax. The new plant should come on stream in late 2021. BASF also has a TPE-based antistatic offering, but in its case it is a polyurethane — Elastostat 10-02 — which it supplies in masterbatch form. Current applications include PP buckets for chemical waste, HDPE intermediate bulk containers, and polysty- rene transport trays for microchips. Future possible applications include blown film. A more recent development, Elastostat 15-01, is for use in other TPUs. One application is hoses that require EU food contact approval, but BASF is also targeting transportation belts and shoe soles.


Serving up ideas Carlos Caro is Project Leader at Grafe Polymer Solutions in Blankenhain, Germany. “For two decades we have been serving the market in the field of electrically conductive compounds for the production of things like storage boxes in auto- matic warehouse systems where sensitive parts are handled or where unexpected electric discharges need to be avoided for safety reasons,” he says. “In the last years we have been seeing a switch for two kind of applications : either for low cost products or for high performance ones. In order to improve the mechanical properties of the whole compound low cost electrically conductive compounds contain a certain amount of recycled and/or regranulated resins paired with new, virgin polymer. The quality of this recycled material and the ratio of new resin are crucial for the quality of the whole compound influencing the final price of the product,” he says. The volumes for these relatively low-cost compounds are high but the competition is tough, says Caro. “Our job as a compound producer is, therefore, to find the perfect balance between material costs and quality in terms of mechanical properties.” Meanwhile, although the quantities and con- sumption in high performance applications are smaller in comparison to low-cost ones, Grafe’s flexible middle scale production and laboratory capacities allow it to develop and produce custom- ised materials for many projects in a faster way, Caro claims. Masterbatch specialist Colloids has undertaken a development programme to improve the performance characteristics of its E-Tec range of electrically conductive products. E-Tec grades, based on both commodity and engineering polymers, offer customers enhanced electrical


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