E-News Update
February 2010



Materials News

New grades of CNTs expand possibilities
With CNTs creating interest in the market, Bayer MaterialScience (BMS) has introduced an improved CNT grade and CNT-based conductive inks while Arkema has expanded its Graphistrength range of products.

Compared with the existing product Baytubes C150P, BMS says its new C70P CNT family is characterised by improved dispersibility, making them highly suited to use in mechanically sensitive polymers. Furthermore, economic advantages can result from the shorter times required to disperse the nanotube agglomerates in water and other low-viscosity liquids.
Multi-wall CNTs, with their very large length-to-diameter ratio, display very high tensile strength and exceptional electrical and thermal conductivity.

Baytubes are agglomerated CNTs and offer a very high degree of purity. The agglomerates can be easily and safely handled and efficiently processed. Even small amounts are capable of imparting new properties to dispersions, plastics, metals and other materials. The potential fields of application for these modified materials range from sporting goods to the electronics industry and mechanical engineering.

Recently, BMS announced a new pilot plant for CNTs with an annual capacity of 200 tonnes in Leverkusen.

The German company has also introduced two CNT-based conductive inks BayInk TPS and TP CNT, which have been developed primarily for use in the growing "printed electronics" market. These new inks boast excellent adhesion to plastic films, other flexible substrates, glass, silicone and indium tin oxide (ITO), where they form highly stable structures. They also have the potential for use in conventional electronic components, where they can replace the complex process of metallisation.

To date, there are only a few examples of applications for producing electronic circuits using printable inks. The technology is deployed in manufacturing RFID chips and certain film displays, for instance. But experts believe printed electronics offers significant market potential and expect to see it expand rapidly. Future areas of application could include e-books or rollable screens but also electrically conductive structures in vehicles, such as integrated receiving antennae for navigation systems.

Meanwhile, French company Arkema has, since it started producing CNTs in 2006, been developing new products. It has now introduced what it says is the first universal CNT masterbatch for thermoplastics.

Graphistrength CM12-30 has a 30% CNT content and is suitable for use in polyamides, polyesters, polycarbonate and acetals. Arkema will shortly be introducing a grade for polyolefins, for the sheathing of cables or the coating of components for electronics applications requiring ESD properties. CM12-30 can be fully diluted within the thermoplastic matrix, allowing homogeneous dispersion of CNTs to produce compounds with improved electrostatic dissipation properties for low CNT concentrations in the finished material.

Its other grades, Graphistrength CE1-20, CE2-40 and CE3-35, contain up to 40% CNTs and are specifically designed for elastomers – fluoroelastomer, nitrile, and silicone. These products are used to produce materials that combine ESD properties with high mechanical strength for low CNT concentrations, such as elongation at break. One potential application is the manufacture of joints with ESD properties, which are needed in the automotive and aerospace industries.

It also has two solid concentrates for liquid epoxy and aqueous solutions with increased CNT content. Arkema says liquid epoxy dispersions already on the market are designed to boost the mechanical strength and the conductivity of epoxy composites, but their low CNT content (of few per cent) limits variation of the formulation. Its new solid granule concentrates contain up to 25% CNTs and can be fully dispersed in liquid epoxy and aqueous solutions. Applications are in composites and in adhesives, ink or paint.

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