Graphene nanotubes for PU applications
According to the Luxembourg-based company OCSiAl, its graphene nanotubes have demonstrated their ability to impart permanent and homogeneous anti-static properties to polyurethane materials, overcoming previous difficulties with nanotube dispersion in PU systems. The recently developed nanotube-based concentrate Tuball Matrix 202 has already built up a solid track record in applications such as industrial rollers and castors, PU shoes, printing rollers and cleaning pigs, said the company.
Tuball graphene nanotubes are used, e.g., in customer-oriented applications with high-performance requirements. One example is PU discs in cleaning pigs for industrial pipelines. To avoid explosions and fires while also preventing static noise and improving diagnostic accuracy, manufacturers of cleaning pigs are replacing ammonium salts as an anti-static agent with Tuball Matrix 202. In addition to a permanent and stable resistivity level of 107 – 105 Ω·cm, the preliminary results have shown a 30 % reduction in the rate of equipment failure, said OCSiAl.
Another specific application of Tuball Matrix 202 is anti-static shoes, where the PU elastomer material used in the outsole and midsole allows the shoes to be used in various static-sensitive facilities in the chemistry, oil and gas, electronics and mining industries. According to the manufacturer, these nanotubes have also been well received by industrial roller manufacturers, as PU printing rollers can now be produced with a permanent volume resistivity level of 108 – 106 Ω·cm without dust formation at the facility and while preserving the mechanical performance characteristics such as abrasion resistance and hardness. Tuball Matrix 202 is also finding applications in rollers and castors used in the mining industry, where anti-static properties are critical for safety reasons. According to data supplied by one of OCSiAl’s customers, graphene nanotubes preserve or even improve mechanical properties of the system, whereas previously the 6.5 wt% of carbon black that had been used for anti-static purposes led to a nearly two-fold reduction in tear strength.
The Tuball Matrix 202 concentrate carrier is a plasticiser based on fatty carboxylic acid ester derivatives. To obtain a resistivity level of 109 – 105 Ω·cm, the working dosage range of graphene nanotubes is 100 times less than the working dosage of ammonium salts, 500 times less than that of carbon black, and 1000 times less than that of conductive mica, said OCSiAl. In comparison with ammonium salts, graphene nanotubes enable a wider range of resistivity levels that are independent of humidity and temperature conditions, while their advantages over carbon black is rooted in their easy dispersion and the preserved mechanical properties of the system.