Rolls accumulate triboelectric charge when they move against cylinders, wool, paper, or any other insulator. This charge can then cause paper jams and unwanted changes in tinting, toner density, reduction in the efficiency and the overall quality of the production and printing process. These problems can be vastly reduced by modifying the composition of a normally non-conductive polymer roller so that it has anti-static or ESD properties. Up to now, the most common anti-static additives to satisfy the requirements have been carbon black or special mineral/organic fillers. However, the high loadings of around 20% by weight required in the total compound lead to degradation of mechanical properties and a reduction in the life-cycle, as well as problems with non-permanent and non-uniform conductivity and migration of carbon black to the surface, which is a particular problem in itself to printing applications.
TUBALL single wall carbon nanotubes should be referred to as graphene nanotubes because each nanotube is an extremely thin rolled-up sheet of graphene. Thanks to their extraordinary physical and chemical properties, TUBALL graphene nanotubes are an ideal conductive additive in various types of rollers used in printing devices and industrial applications involving pigments, organic solvents and other aggressive environments. These nanotubes facilitate permanent and homogeneous conductivity without a negative impact on the mechanical properties of the original materials; in some cases, the nanotubes can even improve them. Solutions containing TUBALL are available for a wide range of polymers. For example, a South African producer of urethane acrylate resin printing rollers has replaced 20% of a carbon black additive with just 0.4% of TUBALL MATRIX 201 nanotube-based concentrate. This achieved a homogeneous, permanent and humidity-independent surface resistivity of 10^6 Ω/sq, without negativally effecting the mechanical properties, with increased abrasion resistance and prolonged life-cycle.
As a further example, a Russian producer of hot-cast PU rollers for rotation of wool fiber is now using 0.5% of TUBALL MATRIX 202 nanotube-based concentrate to achieve a uniform and stable surface resistivity level of 10^9 Ω/sq. Lab-scale testing has confirmed an increase in abrasion resistance, though further testing still needs to be done. TUBALL nanotubes are also proving to be the additive of choice for silicone roller producers. In silicone-based rollers, just 1% of TUBALL MATRIX 605 concentrate enables uniform and stable resistivity of 10^8 Ω·cm along with the option to produce bright colours. Based on this concentrate, Asian companies are now able to produce a range of conductive coloured silicone products without the migration of carbon to the surface of rollers.
The product line of TUBALL MATRIX concentrates that is now available for various standard formulations of industrial rollers meets conductivity standards without compromising mechanical properties. In fact, the potential of TUBALL nanotubes to improve both static and dynamic mechanical properties and thus prolong the life-cycle of industrial rollers is attracting great interest from the industry.