Coatings World - March 2017

Single Wall Carbon Nanotubes
March 2017 www.coatingsworld.com Coatings World | 81

resin (AROPOL M 105). Performance in the different systems was validated by Technische Universität Hamburg-Harburg (TUHH). All measurements were conducted according to ASTM D257.

Now that the loading requirement to achieve the targeted conductivity level can be significantly reduced, several other material properties can also be enabled. For example, in contrast to traditional additives that turn materials black, the low loadings of nanotubes enable manufacturers to achieve a variety of colors (Figure 2).

In addition to color enablement, nanotubes can provide an improved surface finish, reduced thickness, and allow new properties through secondary additives. In terms of surface finish, the uniform dispersion of single wall carbon nanotubes provides topcoats with an extremely smooth and glossy surface, which is not possible with most other conductive additives.

The ability to use extremely low additive amounts also allows manufacturers of ESD control flooring to develop products with reduced thickness. By adding single wall carbon nanotubes into conductive coatings, manufacturers can reduce thickness as low as 25 micron DFT, creating possibilities for a variety of vertical and other conductive paint applications. Moreover, the time required to maintain or coat an ultra-thin ESD control epoxy or polyurethane topcoat with nanotubes can be significantly reduced, yielding additional cost savings.

The ability to vary the dosage of single wall carbon nano-
tubes also leaves room for manufacturers to develop other
required characteristics, such as thermal conductivity and
mechanical property improvements, through secondary ad-
ditives that could not be loaded otherwise. For example, im-
proving the abrasion, impact and scratch resistance3 of epoxy
compounds could be of great value in facilities where heavy
forklift traffic occurs.

Nanotube Solutions

In spite of the superiority of single wall carbon nanotubes over other conductive additives, they were not widely available until recently due to a number of reasons that are critically important to manufacturers: high price, the absence of industrial-scale production technology, and issues related to dispersion and preventing agglomeration of nanotubes.

These issues have now been resolved. Headquartered in Luxembourg and with operations worldwide, global manufacturer OCSiAl launched the first plant for industrial-scale production of single wall carbon nanotubes. Its product TUBALL™, which consists of 80% or more of single wall carbon nanotubes, is the first product of its kind to make single wall carbon nanotubes available for large commercial applications.

OCSiAl entered the market in 2014 with unparalleled production volumes, measured in tonnes of nanotubes, and an attractive price 75 times lower than that of the nearest analogue. A number of unique technologies are incorporated that not only prevent nanotubes from further agglomeration, but also simplify the addition of the already well-dispersed nanotubes into material systems.

Today there are several single wall carbon nanotube-based concentrates for ESD control floorings available on the market – TUBALL MATRIX for epoxy, polyester and other resins and TUBALL COAT for water-based systems. These concentrates have been developed for easy use and specifically designed for resins and coatings. One example of a commercially successful product based on nanotubes is a line of anti-static epoxy flooring developed by one of the largest Russian flooring companies, TEOHIM. An extremely low dosage of 0.01 wt.% of TUBALL provides their compounds

Figure 1. Volume resistivity in epoxy and polyester resin at various loadings of single wall carbon nanotube additive. Performance in different systems validated by Technische Universität Hamburg-Harburg (TUHH). Tested in epoxy resin D.E.R. 330 and polyester resin AROPOL M 105. Measurements conducted according to ASTM D257 standard.